Index: wp-signup.php
===================================================================
--- wp-signup.php	(revision 22229)
+++ wp-signup.php	(working copy)
@@ -12,6 +12,11 @@
 	die();
 }
 
+/**
+ * Prints signup_header via wp_head
+ *
+ * @since 3.0.0
+ */
 function do_signup_header() {
 	do_action( 'signup_header' );
 }
@@ -30,6 +35,14 @@
 // Fix for page title
 $wp_query->is_404 = false;
 
+/**
+ * Prints styles for front-end Multisite signup pages.
+ *
+ * The default styles are printed via signup_header which is hooked to wp_head. 
+ * They can be overloaded by replacing the output on the signup_header action hook.
+ *
+ * @since 3.0.0
+ */
 function wpmu_signup_stylesheet() {
 	?>
 	<style type="text/css">
@@ -50,7 +63,6 @@
 	<?php
 }
 
-add_action( 'wp_head', 'wpmu_signup_stylesheet' );
 get_header();
 
 do_action( 'before_signup_form' );
@@ -58,6 +70,15 @@
 <div id="content" class="widecolumn">
 <div class="mu_register">
 <?php
+/**
+ * Generates and displays the Signup and Create Site forms
+ *
+ * @since 3.0.0
+ *
+ * @param string $blogname
+ * @param string $blog_title
+ * @param array $errors
+ */
 function show_blog_form($blogname = '', $blog_title = '', $errors = '') {
 	global $current_site;
 	// Blog name
@@ -112,6 +133,14 @@
 	do_action('signup_blogform', $errors);
 }
 
+/**
+ * {@internal Missing Short Description}}
+ *
+ * @since 3.0.0
+ *
+ * @uses wp_get_current_user()
+ * @return array
+ */
 function validate_blog_form() {
 	$user = '';
 	if ( is_user_logged_in() )
@@ -120,6 +149,15 @@
 	return wpmu_validate_blog_signup($_POST['blogname'], $_POST['blog_title'], $user);
 }
 
+/**
+ * {@internal Missing Short Description}}
+ *
+ * @since 3.0.0
+ *
+ * @param string $user_name
+ * @param string $user_email
+ * @param array $errors
+ */
 function show_user_form($user_name = '', $user_email = '', $errors = '') {
 	// User name
 	echo '<label for="user_name">' . __('Username:') . '</label>';
@@ -142,10 +180,27 @@
 	do_action( 'signup_extra_fields', $errors );
 }
 
+/**
+ * {@internal Missing Short Description}}
+ *
+ * @since 3.0.0
+ *
+ * @return array
+ */
 function validate_user_form() {
 	return wpmu_validate_user_signup($_POST['user_name'], $_POST['user_email']);
 }
 
+/**
+ * {@internal Missing Short Description}}
+ *
+ * @since 3.0.0
+ *
+ * @uses wp_get_current_user()
+ * @param string $blogname
+ * @param string $blog_title
+ * @param array $errors
+ */
 function signup_another_blog($blogname = '', $blog_title = '', $errors = '') {
 	global $current_site;
 	$current_user = wp_get_current_user();
@@ -191,6 +246,14 @@
 	<?php
 }
 
+/**
+ * {@internal Missing Short Description}}
+ *
+ * @since 3.0.0
+ *
+ * @uses validate_blog_form()
+ * @return bool
+ */
 function validate_another_blog_signup() {
 	global $wpdb, $blogname, $blog_title, $errors, $domain, $path;
 	$current_user = wp_get_current_user();
@@ -214,6 +277,17 @@
 	return true;
 }
 
+/**
+ * {@internal Missing Short Description}}
+ *
+ * @since 3.0.0
+ *
+ * @param string $domain
+ * @param string $path
+ * @param string $user_name
+ * @param string $user_email
+ * @param string $meta
+ */
 function confirm_another_blog_signup($domain, $path, $blog_title, $user_name, $user_email = '', $meta = '') {
 	?>
 	<h2><?php printf( __( 'The site %s is yours.' ), "<a href='http://{$domain}{$path}'>{$blog_title}</a>" ) ?></h2>
@@ -224,6 +298,16 @@
 	do_action( 'signup_finished' );
 }
 
+/**
+ * {@internal Missing Short Description}}
+ *
+ * @since 3.0.0
+ *
+ * @uses apply_filters()
+ * @param string $user_name
+ * @param string $user_email
+ * @param array $errors
+ */
 function signup_user($user_name = '', $user_email = '', $errors = '') {
 	global $current_site, $active_signup;
 
@@ -265,6 +349,17 @@
 	<?php
 }
 
+/**
+ * {@internal Missing Short Description}}
+ *
+ * @since 3.0.0
+ *
+ * @uses signup_user()
+ * @uses signup_blog()
+ * @uses wpmu_signup_user()
+ * @uses confirm_user_signup()
+ * @return bool
+ */
 function validate_user_signup() {
 	$result = validate_user_form();
 	extract($result);
@@ -285,6 +380,14 @@
 	return true;
 }
 
+/**
+ * {@internal Missing Short Description}}
+ *
+ * @since 3.0.0
+ *
+ * @param string $user_name
+ * @param string $user_email
+ */
 function confirm_user_signup($user_name, $user_email) {
 	?>
 	<h2><?php printf( __( '%s is your new username' ), $user_name) ?></h2>
@@ -295,6 +398,19 @@
 	do_action( 'signup_finished' );
 }
 
+/**
+ * {@internal Missing Short Description}}
+ *
+ * @since 3.0.0
+ *
+ * @uses apply_filters()
+ * @uses show_blog_form()
+ * @param string $user_name
+ * @param string $user_email
+ * @param string $blogname
+ * @param string $blog_title
+ * @param array $errors
+ */
 function signup_blog($user_name = '', $user_email = '', $blogname = '', $blog_title = '', $errors = '') {
 	if ( !is_wp_error($errors) )
 		$errors = new WP_Error();
@@ -321,6 +437,18 @@
 	<?php
 }
 
+/**
+ * {@internal Missing Short Description}}
+ *
+ * @since 3.0.0
+ *
+ * @uses wpmu_validate_user_signup()
+ * @uses wpmu_validate_blog_signup()
+ * @uses signup_user()
+ * @uses signup_blog()
+ * @uses apply_filters()
+ * @return bool
+ */
 function validate_blog_signup() {
 	// Re-validate user info.
 	$result = wpmu_validate_user_signup($_POST['user_name'], $_POST['user_email']);
@@ -348,6 +476,18 @@
 	return true;
 }
 
+/**
+ * {@internal Missing Short Description}}
+ *
+ * @since 3.0.0
+ *
+ * @param string $domain
+ * @param string $path
+ * @param string $blog_title
+ * @param string $user_name
+ * @param string $user_email
+ * @param string $meta
+ */
 function confirm_blog_signup($domain, $path, $blog_title, $user_name = '', $user_email = '', $meta) {
 	?>
 	<h2><?php printf( __( 'Congratulations! Your new site, %s, is almost ready.' ), "<a href='http://{$domain}{$path}'>{$blog_title}</a>" ) ?></h2>
Index: wp-includes/default-filters.php
===================================================================
--- wp-includes/default-filters.php	(revision 22229)
+++ wp-includes/default-filters.php	(working copy)
@@ -213,6 +213,7 @@
 add_action( 'wp_print_footer_scripts', '_wp_footer_scripts'                 );
 add_action( 'init',                'check_theme_switched',            99    );
 add_action( 'after_switch_theme',  '_wp_sidebars_changed'                   );
+add_action( 'signup_header',       'wpmu_signup_stylesheet'                 );
 
 if ( isset( $_GET['replytocom'] ) )
     add_action( 'wp_head', 'wp_no_robots' );