diff --git a/wp-includes/ms-functions.php b/wp-includes/ms-functions.php
index 976fcbc22..b3b21dfaa 100644
--- a/wp-includes/ms-functions.php
+++ b/wp-includes/ms-functions.php
@@ -60,9 +60,6 @@ function get_admin_users_for_domain( $sitedomain = '', $path = '' ) {
  * @since MU 1.0
  * @uses get_blogs_of_user()
  * @uses add_user_to_blog()
- * @uses update_user_meta()
- * @uses wp_cache_delete()
- * @uses get_user_meta()
  * @uses get_blog_details()
  *
  * @param int $user_id The unique ID of the user
@@ -151,7 +148,6 @@ function is_user_member_of_blog( $user_id, $blog_id = 0 ) {
  * The count is cached and updated twice daily. This is not a live count.
  *
  * @since MU 2.7
- * @uses update_site_option()
  *
  * @return int
  */
@@ -165,7 +161,6 @@ function get_user_count() {
  * The count is cached and updated twice daily. This is not a live count.
  *
  * @since MU 1.0
- * @uses update_site_option()
  *
  * @param int $id Optional. A site_id.
  * @return int
@@ -203,10 +198,6 @@ function get_blog_post( $blog_id, $post_id ) {
  * users are added to a blog.
  *
  * @since MU 1.0
- * @uses switch_to_blog()
- * @uses update_user_meta()
- * @uses wp_cache_delete()
- * @uses restore_current_blog()
  *
  * @param int $blog_id ID of the blog you're adding the user to.
  * @param int $user_id ID of the user you're adding.
@@ -245,11 +236,6 @@ function add_user_to_blog( $blog_id, $user_id, $role ) {
  * reassign the user's blog posts to another user upon removal.
  *
  * @since MU 1.0
- * @uses switch_to_blog()
- * @uses get_user_meta()
- * @uses get_blogs_of_user()
- * @uses update_user_meta()
- * @uses restore_current_blog()
  *
  * @param int $user_id ID of the user you're removing.
  * @param int $blog_id ID of the blog you're removing the user from.
@@ -307,15 +293,13 @@ function remove_user_from_blog($user_id, $blog_id = '', $reassign = '') {
  * Create an empty blog.
  *
  * @since MU 1.0
- * @uses switch_to_blog()
  * @uses install_blog()
- * @uses restore_current_blog()
  *
  * @param string $domain The new blog's domain.
  * @param string $path The new blog's path.
  * @param string $string The new blog's title.
  * @param int $site Optional. Defaults to 1.
- * @return int $blog_id The ID of the newly created blog
+ * @return int The ID of the newly created blog
  */
 function create_empty_blog( $domain, $path, $weblog_title, $site_id = 1 ) {
 	$domain			= addslashes( $domain );
@@ -346,14 +330,10 @@ function create_empty_blog( $domain, $path, $weblog_title, $site_id = 1 ) {
  * Get the permalink for a post on another blog.
  *
  * @since MU 1.0
- * @uses wp_cache_get()
- * @uses switch_to_blog()
- * @uses restore_current_blog()
- * @uses wp_cache_add()
  *
  * @param int $_blog_id ID of the source blog.
  * @param int $post_id ID of the desired post.
- * @return string $link The post's permalink
+ * @return string The post's permalink
  */
 function get_blog_permalink( $_blog_id, $post_id ) {
 	$key = "{$_blog_id}-{$post_id}-blog_permalink";
@@ -376,12 +356,10 @@ function get_blog_permalink( $_blog_id, $post_id ) {
  * $domain is 'blog1.example.com' and $path is '/'.
  *
  * @since MU 2.6.5
- * @uses wp_cache_get()
- * @uses wp_cache_set()
  *
  * @param string $domain
  * @param string $path Optional. Not required for subdomain installations.
- * @return int $id
+ * @return int
  */
 function get_blog_id_from_url( $domain, $path = '/' ) {
 	global $wpdb;
@@ -407,8 +385,24 @@ function get_blog_id_from_url( $domain, $path = '/' ) {
 	return $id;
 }
 
-// wpmu admin functions
+// Admin functions
 
+/**
+ * Redirect a user based on $_GET or $_POST arguments.
+ *
+ * The function looks for redirect arguments in the following order:
+ * 1) $_GET['ref']
+ * 2) $_POST['ref']
+ * 3) $_SERVER['HTTP_REFERER']
+ * 4) $_GET['redirect']
+ * 5) $_POST['redirect']
+ * 6) $url
+ *
+ * @since MU
+ * @uses wpmu_admin_redirect_add_updated_param()
+ *
+ * @param string $url
+ */
 function wpmu_admin_do_redirect( $url = '' ) {
 	$ref = '';
 	if ( isset( $_GET['ref'] ) )
@@ -437,6 +431,14 @@ function wpmu_admin_do_redirect( $url = '' ) {
 	exit();
 }
 
+/**
+ * Adds an 'updated=true' argument to a URL.
+ *
+ * @since MU
+ *
+ * @param string $url
+ * @return string
+ */
 function wpmu_admin_redirect_add_updated_param( $url = '' ) {
 	if ( strpos( $url, 'updated=true' ) === false ) {
 		if ( strpos( $url, '?' ) === false )
@@ -447,6 +449,19 @@ function wpmu_admin_redirect_add_updated_param( $url = '' ) {
 	return $url;
 }
 
+/**
+ * Checks an email address against a list of banned domains.
+ *
+ * This function checks against the Banned Email Domains list
+ * at wp-admin/network/settings.php. The check is only run on
+ * self-registrations; user creation at wp-admin/network/users.php
+ * bypasses this check. 
+ *
+ * @since MU
+ *
+ * @param string $user_email The email provided by the user at registration.
+ * @return bool Returns true when the email address is banned.
+ */
 function is_email_address_unsafe( $user_email ) {
 	$banned_names = get_site_option( 'banned_email_domains' );
 	if ($banned_names && !is_array( $banned_names ))
@@ -470,6 +485,30 @@ function is_email_address_unsafe( $user_email ) {
 	return false;
 }
 
+/**
+ * Processes new user registrations.
+ *
+ * Checks the data provided by the user during signup. Verifies
+ * the validity and uniqueness of user names and user email addresses,
+ * and checks email addresses against admin-provided domain
+ * whitelists and blacklists.
+ *
+ * The hook 'wpmu_validate_user_signup' provides an easy way
+ * to modify the signup process. The value $result, which is passed
+ * to the hook, contains both the user-provided info and the error
+ * messages created by the function. 'wpmu_validate_user_signup' allows
+ * you to process the data in any way you'd like, and unset the
+ * relevant errors if necessary.
+ *
+ * @since MU
+ * @uses is_email_address_unsafe()
+ * @uses username_exists()
+ * @uses email_exists()
+ *
+ * @param string $user_name The login name provided by the user.
+ * @param string $user_email The email provided by the user.
+ * @return array Contains username, email, and error messages.
+ */
 function wpmu_validate_user_signup($user_name, $user_email) {
 	global $wpdb;
 
@@ -562,6 +601,28 @@ function wpmu_validate_user_signup($user_name, $user_email) {
 	return apply_filters('wpmu_validate_user_signup', $result);
 }
 
+/**
+ * Processes new site registrations.
+ *
+ * Checks the data provided by the user during blog signup. Verifies
+ * the validity and uniqueness of blog paths and domains.
+ *
+ * This function prevents the current user from registering a new site
+ * with a blogname equivalent to another user's login name. Passing the
+ * $user parameter to the function, where $user is the other user, is
+ * effectively an override of this limitation.
+ *
+ * Filter 'wpmu_validate_blog_signup' if you want to modify 
+ * the way that WordPress validates new site signups.
+ *
+ * @since MU
+ * @uses domain_exists()
+ * @uses username_exists()
+ *
+ * @param string $blogname The blog name provided by the user. Must be unique.
+ * @param string $blog_title The blog title provided by the user.
+ * @return array Contains the new site data and error messages.
+ */
 function wpmu_validate_blog_signup($blogname, $blog_title, $user = '') {
 	global $wpdb, $domain, $base, $current_site;
 
@@ -645,8 +706,19 @@ function wpmu_validate_blog_signup($blogname, $blog_title, $user = '') {
 	return apply_filters('wpmu_validate_blog_signup', $result);
 }
 
-// Record signup information for future activation. wpmu_validate_signup() should be run
-// on the inputs before calling wpmu_signup().
+/**
+ * Record site signup information for future activation.
+ *
+ * @since MU
+ * @uses wpmu_signup_blog_notification()
+ *
+ * @param string $domain The requested domain.
+ * @param string $path The requested path.
+ * @param string $title The requested site title.
+ * @param string $user The user's requested login name.
+ * @param string $user_email The user's email address.
+ * @param array $meta By default, contains the requested privacy setting and lang_id.
+ */
 function wpmu_signup_blog($domain, $path, $title, $user, $user_email, $meta = '') {
 	global $wpdb;
 
@@ -670,6 +742,19 @@ function wpmu_signup_blog($domain, $path, $title, $user, $user_email, $meta = ''
 	wpmu_signup_blog_notification($domain, $path, $title, $user, $user_email, $key, $meta);
 }
 
+/**
+ * Record user signup information for future activation.
+ *
+ * This function is used when user registration is open but
+ * new site registration is not.
+ *
+ * @since MU
+ * @uses wpmu_signup_user_notification()
+ *
+ * @param string $user The user's requested login name.
+ * @param string $user_email The user's email address.
+ * @param array $meta By default, this is an empty array.
+ */
 function wpmu_signup_user($user, $user_email, $meta = '') {
 	global $wpdb;
 
@@ -693,7 +778,30 @@ function wpmu_signup_user($user, $user_email, $meta = '') {
 	wpmu_signup_user_notification($user, $user_email, $key, $meta);
 }
 
-// Notify user of signup success.
+/**
+ * Notify user of signup success.
+ *
+ * This is the notification function used when site registration
+ * is enabled.
+ *
+ * Filter 'wpmu_signup_blog_notification' to bypass this function or
+ * replace it with your own notification behavior.
+ *
+ * Filter 'wpmu_signup_blog_notification_email' and
+ * 'wpmu_signup_blog_notification_email' to change the content
+ * and subject line of the email sent to newly registered users.
+ *
+ * @since MU
+ *
+ * @param string $domain The new blog domain.
+ * @param string $path The new blog path.
+ * @param string $title The site title.
+ * @param string $user The user's login name.
+ * @param string $user_email The user's email address.
+ * @param array $meta By default, contains the requested privacy setting and lang_id.
+ * @param string $key The activation key created in wpmu_signup_blog()
+ * @return bool
+ */
 function wpmu_signup_blog_notification($domain, $path, $title, $user, $user_email, $key, $meta = '') {
 	global $current_site;
 
@@ -734,6 +842,27 @@ function wpmu_signup_blog_notification($domain, $path, $title, $user, $user_emai
 	return true;
 }
 
+/**
+ * Notify user of signup success.
+ *
+ * This is the notification function used when no new site has
+ * been requested.
+ *
+ * Filter 'wpmu_signup_user_notification' to bypass this function or
+ * replace it with your own notification behavior.
+ *
+ * Filter 'wpmu_signup_user_notification_email' and
+ * 'wpmu_signup_user_notification_subject' to change the content
+ * and subject line of the email sent to newly registered users.
+ *
+ * @since MU
+ *
+ * @param string $user The user's login name.
+ * @param string $user_email The user's email address.
+ * @param array $meta By default, an empty array.
+ * @param string $key The activation key created in wpmu_signup_user()
+ * @return bool
+ */
 function wpmu_signup_user_notification($user, $user_email, $key, $meta = '') {
 	if ( !apply_filters('wpmu_signup_user_notification', $user, $user_email, $key, $meta) )
 		return false;
@@ -765,6 +894,26 @@ function wpmu_signup_user_notification($user, $user_email, $key, $meta = '') {
 	return true;
 }
 
+/**
+ * Activate a signup.
+ *
+ * Hook to 'wpmu_activate_user' or 'wpmu_activate_blog' for events
+ * that should happen only when users or sites are self-created (since
+ * those actions are not called when users and sites are created
+ * by a Super Admin).
+ *
+ * @since MU
+ * @uses wp_generate_password()
+ * @uses wpmu_welcome_user_notification()
+ * @uses add_user_to_blog()
+ * @uses add_new_user_to_blog()
+ * @uses wpmu_create_user()
+ * @uses wpmu_create_blog()
+ * @uses wpmu_welcome_notification()
+ *
+ * @param string $key The activation key provided to the user.
+ * @return array An array containing information about the activated user and/or blog
+ */
 function wpmu_activate_signup($key) {
 	global $wpdb, $current_site;
 
@@ -830,6 +979,22 @@ function wpmu_activate_signup($key) {
 	return array('blog_id' => $blog_id, 'user_id' => $user_id, 'password' => $password, 'title' => $signup->title, 'meta' => $meta);
 }
 
+/**
+ * Create a user.
+ *
+ * This function runs when a user self-registers as well as when
+ * a Super Admin creates a new user. Hook to 'wpmu_new_user' for events
+ * that should affect all new users, but only on Multisite (otherwise
+ * use 'user_register').
+ *
+ * @since MU
+ * @uses wp_create_user()
+ *
+ * @param string $user_name The new user's login name.
+ * @param string $password The new user's password.
+ * @param string $email The new user's email address.
+ * @return mixed Returns false on failure, or int $user_id on success
+ */
 function wpmu_create_user( $user_name, $password, $email) {
 	$user_name = preg_replace( '/\s+/', '', sanitize_user( $user_name, true ) );
 
@@ -846,6 +1011,32 @@ function wpmu_create_user( $user_name, $password, $email) {
 	return $user_id;
 }
 
+/**
+ * Create a site.
+ *
+ * This function runs when a user self-registers a new site as well
+ * as when a Super Admin creates a new site. Hook to 'wpmu_new_blog'
+ * for events that should affect all new sites.
+ *
+ * On subdirectory installs, $domain is the same as the main site's
+ * domain, and the path is the subdirectory name (eg 'example.com'
+ * and '/blog1/'). On subdomain installs, $domain is the new subdomain +
+ * root domain (eg 'blog1.example.com'), and $path is '/'.
+ *
+ * @since MU
+ * @uses domain_exists()
+ * @uses insert_blog()
+ * @uses wp_install_defaults()
+ * @uses add_user_to_blog()
+ *
+ * @param string $domain The new site's domain.
+ * @param string $path The new site's path.
+ * @param string $title The new site's title.
+ * @param int $user_id The user ID of the new site's admin.
+ * @param array $meta Optional. Used to set initial site options.
+ * @param int $site_id Optional. Only relevant on multi-network installs.
+ * @return mixed Returns WP_Error object on failure, int $blog_id on success
+ */
 function wpmu_create_blog($domain, $path, $title, $user_id, $meta = '', $site_id = 1) {
 	$domain = preg_replace( '/\s+/', '', sanitize_user( $domain, true ) );
 
@@ -893,6 +1084,17 @@ function wpmu_create_blog($domain, $path, $title, $user_id, $meta = '', $site_id
 	return $blog_id;
 }
 
+/**
+ * Notifies the network admin that a new site has been activated.
+ *
+ * Filter 'newblog_notify_siteadmin' to change the content of
+ * the notification email.
+ *
+ * @since MU
+ *
+ * @param int $blog_id The new site's ID.
+ * @return bool
+ */
 function newblog_notify_siteadmin( $blog_id, $deprecated = '' ) {
 	if ( get_site_option( 'registrationnotification' ) != 'yes' )
 		return false;
@@ -919,6 +1121,17 @@ Disable these notifications: %4s' ), $blogname, $siteurl, $_SERVER['REMOTE_ADDR'
 	return true;
 }
 
+/**
+ * Notifies the network admin that a new user has been activated.
+ *
+ * Filter 'newuser_notify_siteadmin' to change the content of
+ * the notification email.
+ *
+ * @since MU
+ *
+ * @param int $user_id The new user's ID.
+ * @return bool
+ */
 function newuser_notify_siteadmin( $user_id ) {
 	if ( get_site_option( 'registrationnotification' ) != 'yes' )
 		return false;
@@ -941,11 +1154,37 @@ Disable these notifications: %3s'), $user->user_login, $_SERVER['REMOTE_ADDR'],
 	return true;
 }
 
+/**
+ * Check whether a blogname is already taken.
+ *
+ * Used during the new site registration process to ensure
+ * that each blogname is unique.
+ *
+ * @since MU
+ *
+ * @param string $domain The domain to be checked.
+ * @param string $path The path to be checked.
+ * @param int $site_id Optional. Relevant only on multi-network installs.
+ * @return int
+ */
 function domain_exists($domain, $path, $site_id = 1) {
 	global $wpdb;
 	return $wpdb->get_var( $wpdb->prepare("SELECT blog_id FROM $wpdb->blogs WHERE domain = %s AND path = %s AND site_id = %d", $domain, $path, $site_id) );
 }
 
+/**
+ * Store basic site info in the blogs table.
+ *
+ * This function creates a row in the wp_blogs table and returns
+ * the new blog's ID. It is the first step in creating a new blog.
+ *
+ * @since MU
+ *
+ * @param string $domain The domain of the new site.
+ * @param string $path The path of the new site.
+ * @param int $site_id Unless you're running a multi-network install, be sure to set this value to 1.
+ * @return int The ID of the new row
+ */
 function insert_blog($domain, $path, $site_id) {
 	global $wpdb;
 
@@ -960,7 +1199,20 @@ function insert_blog($domain, $path, $site_id) {
 	return $wpdb->insert_id;
 }
 
-// Install an empty blog.  wpdb should already be switched.
+/**
+ * Install an empty blog.
+ *
+ * Creates the new blog tables and options. If calling this function
+ * directly, be sure to use switch_to_blog() first, so that $wpdb
+ * points to the new blog.
+ *
+ * @since MU
+ * @uses make_db_current_silent()
+ * @uses populate_roles()
+ *
+ * @param int $blog_id The value returned by insert_blog().
+ * @param string $blog_title The title of the new site.
+ */
 function install_blog($blog_id, $blog_title = '') {
 	global $wpdb, $table_prefix, $wp_roles;
 	$wpdb->suppress_errors();
@@ -999,8 +1251,19 @@ function install_blog($blog_id, $blog_title = '') {
 	$wpdb->suppress_errors( false );
 }
 
-// Deprecated, use wp_install_defaults()
-// should be switched already as $blog_id is ignored.
+/**
+ * Set blog defaults.
+ *
+ * This function creates a row in the wp_blogs table.
+ *
+ * @since MU
+ * @deprecated MU
+ * @deprecated Use wp_install_defaults()
+ * @uses wp_install_defaults()
+ *
+ * @param int $blog_id Ignored in this function.
+ * @param int $user_id
+ */
 function install_blog_defaults($blog_id, $user_id) {
 	global $wpdb;
 
@@ -1013,6 +1276,23 @@ function install_blog_defaults($blog_id, $user_id) {
 	$wpdb->suppress_errors( false );
 }
 
+/**
+ * Notify a user that her blog activation has been successful.
+ *
+ * Filter 'wpmu_welcome_notification' to disable or bypass.
+ *
+ * Filter 'update_welcome_email' and 'update_welcome_subject' to
+ * modify the content and subject line of the notification email.
+ *
+ * @since MU
+ *
+ * @param int $blog_id
+ * @param int $user_id
+ * @param string $password
+ * @param string $title The new blog's title
+ * @param array $meta Optional. Not used in the default function, but is passed along to hooks for customization.
+ * @return bool
+ */
 function wpmu_welcome_notification($blog_id, $user_id, $password, $title, $meta = '') {
 	global $current_site;
 
@@ -1063,6 +1343,21 @@ Thanks!
 	return true;
 }
 
+/**
+ * Notify a user that her account activation has been successful.
+ *
+ * Filter 'wpmu_welcome_user_notification' to disable or bypass.
+ *
+ * Filter 'update_welcome_user_email' and 'update_welcome_user_subject' to
+ * modify the content and subject line of the notification email.
+ *
+ * @since MU
+ *
+ * @param int $user_id
+ * @param string $password
+ * @param array $meta Optional. Not used in the default function, but is passed along to hooks for customization.
+ * @return bool
+ */
 function wpmu_welcome_user_notification($user_id, $password, $meta = '') {
 	global $current_site;
 
@@ -1096,11 +1391,30 @@ function wpmu_welcome_user_notification($user_id, $password, $meta = '') {
 	return true;
 }
 
+/**
+ * Get the current site info.
+ *
+ * Returns an object containing the ID, domain, path, and site_name
+ * of the site being viewed.
+ *
+ * @since MU
+ *
+ * @return object
+ */
 function get_current_site() {
 	global $current_site;
 	return $current_site;
 }
 
+/**
+ * Get a numeric user ID from either an email address or a login.
+ *
+ * @since MU
+ * @uses is_email()
+ *
+ * @param string $string
+ * @return int
+ */
 function get_user_id_from_string( $string ) {
 	$user_id = 0;
 	if ( is_email( $string ) ) {
@@ -1118,6 +1432,18 @@ function get_user_id_from_string( $string ) {
 	return $user_id;
 }
 
+/**
+ * Get a user's most recent post.
+ *
+ * Walks through each of a user's blogs to find the post with
+ * the most recent post_date_gmt.
+ *
+ * @since MU
+ * @uses get_blogs_of_user()
+ *
+ * @param int $user_id
+ * @return array Contains the blog_id, post_id, post_date_gmt, and post_gmt_ts
+ */
 function get_most_recent_post_of_user( $user_id ) {
 	global $wpdb;
 
@@ -1150,7 +1476,20 @@ function get_most_recent_post_of_user( $user_id ) {
 	return $most_recent_post;
 }
 
-/* Misc functions */
+// Misc functions
+
+/**
+ * Get the size of a directory.
+ *
+ * A helper function that is used primarily to check whether
+ * a blog has exceeded its allowed upload space.
+ *
+ * @since MU
+ * @uses recurse_dirsize()
+ *
+ * @param string $directory
+ * @return int
+ */
 function get_dirsize( $directory ) {
 	$dirsize = get_transient( 'dirsize_cache' );
 	if ( is_array( $dirsize ) && isset( $dirsize[ $directory ][ 'size' ] ) )
@@ -1165,6 +1504,17 @@ function get_dirsize( $directory ) {
 	return $dirsize[ $directory ][ 'size' ];
 }
 
+/**
+ * Get the size of a directory recursively.
+ *
+ * Used by get_dirsize() to get a directory's size when it contains
+ * other directories.
+ *
+ * @since MU
+ *
+ * @param string $directory
+ * @return int
+ */
 function recurse_dirsize( $directory ) {
 	$size = 0;
 
@@ -1192,6 +1542,18 @@ function recurse_dirsize( $directory ) {
 	return $size;
 }
 
+/**
+ * Check whether a blog has used its allotted upload space.
+ *
+ * Used by get_dirsize() to get a directory's size when it contains
+ * other directories.
+ *
+ * @since MU
+ * @uses get_dirsize()
+ *
+ * @param bool $echo Optional. If $echo is set and the quota is exceeded, a warning message is echoed. Default is true.
+ * @return int
+ */
 function upload_is_user_over_quota( $echo = true ) {
 	if ( get_site_option( 'upload_space_check_disabled' ) )
 		return false;
@@ -1212,6 +1574,20 @@ function upload_is_user_over_quota( $echo = true ) {
 	}
 }
 
+/**
+ * Check an array of MIME types against a whitelist.
+ *
+ * WordPress ships with a set of allowed upload filetypes, 
+ * which is defined in wp-includes/functions.php in
+ * get_allowed_mime_types(). This function is used to filter
+ * that list against the filetype whitelist provided by Multisite 
+ * Super Admins at wp-admin/network/settings.php. 
+ *
+ * @since MU
+ *
+ * @param array $mimes
+ * @return array
+ */
 function check_upload_mimes( $mimes ) {
 	$site_exts = explode( ' ', get_site_option( 'upload_filetypes' ) );
 	foreach ( $site_exts as $ext ) {
@@ -1223,17 +1599,46 @@ function check_upload_mimes( $mimes ) {
 	return $site_mimes;
 }
 
+/**
+ * Update a blog's post count.
+ *
+ * WordPress MS stores a blog's post count as an option so as
+ * to avoid extraneous COUNTs when a blog's details are fetched
+ * with get_blog_details(). This function is called when posts
+ * are published to make sure the count stays current.
+ *
+ * @since MU
+ */
 function update_posts_count( $deprecated = '' ) {
 	global $wpdb;
 	update_option( 'post_count', (int) $wpdb->get_var( "SELECT COUNT(ID) FROM {$wpdb->posts} WHERE post_status = 'publish' and post_type = 'post'" ) );
 }
 
+/**
+ * Logs user registrations.
+ *
+ * @since MU
+ *
+ * @param int $blog_id
+ * @param int $user_id
+ */
 function wpmu_log_new_registrations( $blog_id, $user_id ) {
 	global $wpdb;
 	$user = new WP_User( (int) $user_id );
 	$wpdb->insert( $wpdb->registration_log, array('email' => $user->user_email, 'IP' => preg_replace( '/[^0-9., ]/', '',$_SERVER['REMOTE_ADDR'] ), 'blog_id' => $blog_id, 'date_registered' => current_time('mysql')) );
 }
 
+/**
+ * Get the remaining upload space for this blog.
+ *
+ * @since MU
+ * @uses upload_is_user_over_quota()
+ * @uses get_space_allowed()
+ * @uses get_dirsize()
+ *
+ * @param int $size
+ * @return int
+ */
 function fix_import_form_size( $size ) {
 	if ( upload_is_user_over_quota( false ) == true )
 		return 0;
@@ -1315,11 +1720,27 @@ function global_terms( $term_id, $deprecated = '' ) {
 	return $global_id;
 }
 
+/**
+ * Ensure that the current site's domain is listed in the allowed redirect host list.
+ *
+ * @see wp_validate_redirect()
+ * @since MU
+ *
+ * @return array The current site's domain
+ */
 function redirect_this_site( $deprecated = '' ) {
 	global $current_site;
 	return array( $current_site->domain );
 }
 
+/**
+ * Check whether an upload is too big.
+ *
+ * @since MU
+ *
+ * @param array $upload
+ * @return mixed If the upload is under the size limit, $upload is returned. Otherwise returns an error message.
+ */
 function upload_is_file_too_big( $upload ) {
 	if ( is_array( $upload ) == false || defined( 'WP_IMPORTING' ) )
 		return $upload;
@@ -1330,12 +1751,27 @@ function upload_is_file_too_big( $upload ) {
 	return $upload;
 }
 
+/**
+ * Add a nonce field to the signup page.
+ *
+ * @since MU
+ * @uses wp_nonce_field()
+ */
 function signup_nonce_fields() {
 	$id = mt_rand();
 	echo "<input type='hidden' name='signup_form_id' value='{$id}' />";
 	wp_nonce_field('signup_form_' . $id, '_signup_form', false);
 }
 
+/**
+ * Process the signup nonce created in signup_nonce_fields().
+ *
+ * @since MU
+ * @uses wp_create_nonce()
+ *
+ * @param array $result
+ * @return array
+ */
 function signup_nonce_check( $result ) {
 	if ( !strpos( $_SERVER[ 'PHP_SELF' ], 'wp-signup.php' ) )
 		return $result;
@@ -1346,6 +1782,11 @@ function signup_nonce_check( $result ) {
 	return $result;
 }
 
+/**
+ * Correct 404 redirects when NOBLOGREDIRECT is defined.
+ *
+ * @since MU
+ */
 function maybe_redirect_404() {
 	global $current_site;
 	if ( is_main_site() && is_404() && defined( 'NOBLOGREDIRECT' ) && ( $destination = apply_filters( 'blog_redirect_404', NOBLOGREDIRECT ) ) ) {
@@ -1356,6 +1797,16 @@ function maybe_redirect_404() {
 	}
 }
 
+/**
+ * Add a new user to a blog by visiting /newbloguser/username/.
+ *
+ * This will only work when the user's details are saved as an option
+ * keyed as 'new_user_x', where 'x' is the username of the user to be
+ * added, as when a user is invited through the regular WP Add User interface.
+ *
+ * @since MU
+ * @uses add_existing_user_to_blog()
+ */	
 function maybe_add_existing_user_to_blog() {
 	if ( false === strpos( $_SERVER[ 'REQUEST_URI' ], '/newbloguser/' ) )
 		return false;
@@ -1376,6 +1827,14 @@ function maybe_add_existing_user_to_blog() {
 	wp_die( sprintf(__('You have been added to this site. Please visit the <a href="%s">homepage</a> or <a href="%s">login</a> using your username and password.'), site_url(), admin_url() ), __('Success') );
 }
 
+/**
+ * Add a user to a blog based on details from maybe_add_existing_user_to_blog().
+ *
+ * @since MU
+ * @uses add_user_to_blog()
+ * 
+ * @param array $details
+ */	
 function add_existing_user_to_blog( $details = false ) {
 	global $blog_id;
 
@@ -1386,6 +1845,15 @@ function add_existing_user_to_blog( $details = false ) {
 	return $result;
 }
 
+/**
+ * Add a newly created user to the appropriate blog
+ *
+ * @since MU
+ * 
+ * @param int $user_id
+ * @param string $email
+ * @param array $meta
+ */	
 function add_new_user_to_blog( $user_id, $email, $meta ) {
 	global $current_site;
 	if ( $meta[ 'add_to_blog' ] ) {
@@ -1397,11 +1865,26 @@ function add_new_user_to_blog( $user_id, $email, $meta ) {
 	}
 }
 
+/**
+ * Correct From host on outgoing mail to match the site domain
+ *
+ * @since MU
+ */	
 function fix_phpmailer_messageid( $phpmailer ) {
 	global $current_site;
 	$phpmailer->Hostname = $current_site->domain;
 }
 
+/**
+ * Check to see whether a user is marked as a spammer, based on username
+ *
+ * @since MU
+ * @uses get_current_user_id()
+ * @uses get_user_id_from_string()
+ *
+ * @param string $username
+ * @return bool
+ */	
 function is_user_spammy( $username = 0 ) {
 	if ( $username == 0 ) {
 		$user_id = get_current_user_id();
@@ -1413,6 +1896,18 @@ function is_user_spammy( $username = 0 ) {
 	return ( isset( $u->spam ) && $u->spam == 1 );
 }
 
+/**
+ * Update this blog's 'public' setting in the global blogs table.
+ *
+ * Public blogs have a setting of 1, private blogs are 0.
+ *
+ * @since MU
+ * @uses update_blog_status()
+ *
+ * @param int $old_value
+ * @param int $value The new public value
+ * @return bool
+ */	
 function update_blog_public( $old_value, $value ) {
 	global $wpdb;
 	do_action('update_blog_public');
@@ -1420,6 +1915,14 @@ function update_blog_public( $old_value, $value ) {
 }
 add_action('update_option_blog_public', 'update_blog_public', 10, 2);
 
+/**
+ * Get the "dashboard blog", the blog where users without a blog edit their profile data.
+ *
+ * @since MU
+ * @uses get_blog_details()
+ *
+ * @return int
+ */	
 function get_dashboard_blog() {
 	if ( $blog = get_site_option( 'dashboard_blog' ) )
 		return get_blog_details( $blog );
@@ -1427,6 +1930,17 @@ function get_dashboard_blog() {
 	return get_blog_details( $GLOBALS['current_site']->blog_id );
 }
 
+/**
+ * Check whether a usermeta key has to do with the current blog.
+ *
+ * @since MU
+ * @uses wp_get_current_user()
+ *
+ * @param string $key
+ * @param int $user_id Optional. Defaults to current user.
+ * @param int $blog_id Optional. Defaults to current blog.
+ * @return bool
+ */	
 function is_user_option_local( $key, $user_id = 0, $blog_id = 0 ) {
 	global $wpdb;
 
@@ -1444,6 +1958,13 @@ function is_user_option_local( $key, $user_id = 0, $blog_id = 0 ) {
 	return false;
 }
 
+/**
+ * Check whether users can self-register, based on Network settings.
+ *
+ * @since MU
+ *
+ * @return bool
+ */	
 function users_can_register_signup_filter() {
 	$registration = get_site_option('registration');
 	if ( $registration == 'all' || $registration == 'user' )
@@ -1453,6 +1974,14 @@ function users_can_register_signup_filter() {
 }
 add_filter('option_users_can_register', 'users_can_register_signup_filter');
 
+/**
+ * Ensure that the welcome message is not empty. Currently unused.
+ *
+ * @since MU
+ *
+ * @param string $text
+ * @return string
+ */	
 function welcome_user_msg_filter( $text ) {
 	if ( !$text ) {
 		return __( 'Dear User,
@@ -1540,4 +2069,4 @@ function wp_update_network_counts() {
 	update_site_option( 'user_count', $count );
 }
 
-?>
+?>
\ No newline at end of file