Index: wp-includes/deprecated.php
===================================================================
--- wp-includes/deprecated.php	(revision 19015)
+++ wp-includes/deprecated.php	(working copy)
@@ -2870,3 +2870,20 @@
 			$wp_admin_bar->add_menu( array( 'id' => 'dashboard', 'title' => __( 'Dashboard' ), 'href' => admin_url() ) );
 	}
 }
+
+/**
+ * Checks if the current user belong to a given blog.
+ *
+ * @since MU
+ * @deprecated 3.3
+ * @deprecated Use is_user_member_of_blog()
+ * @see is_user_member_of_blog()
+ *
+ * @param int $blog_id Blog ID
+ * @return bool True if the current users belong to $blog_id, false if not.
+ */
+function is_blog_user( $blog_id = 0 ) {
+	_deprecated_function( __FUNCTION__, '3.3', 'is_user_member_of_blog()' );
+
+	return is_user_member_of_blog( get_current_user_id(), $blog_id );
+}
Index: wp-includes/ms-functions.php
===================================================================
--- wp-includes/ms-functions.php	(revision 19015)
+++ wp-includes/ms-functions.php	(working copy)
@@ -119,32 +119,6 @@
 }
 
 /**
- * Find out whether a user is a member of a given blog.
- *
- * @since MU 1.1
- * @uses get_blogs_of_user()
- *
- * @param int $user_id The unique ID of the user
- * @param int $blog Optional. If no blog_id is provided, current site is used
- * @return bool
- */
-function is_user_member_of_blog( $user_id, $blog_id = 0 ) {
-	$user_id = (int) $user_id;
-	$blog_id = (int) $blog_id;
-
-	if ( $blog_id == 0 ) {
-		global $wpdb;
-		$blog_id = $wpdb->blogid;
-	}
-
-	$blogs = get_blogs_of_user( $user_id );
-	if ( is_array( $blogs ) )
-		return array_key_exists( $blog_id, $blogs );
-	else
-		return false;
-}
-
-/**
  * The number of active users in your installation.
  *
  * The count is cached and updated twice daily. This is not a live count.
Index: wp-includes/user.php
===================================================================
--- wp-includes/user.php	(revision 19015)
+++ wp-includes/user.php	(working copy)
@@ -720,22 +720,32 @@
 }
 
 /**
- * Checks if the current user belong to a given blog.
+ * Find out whether a user is a member of a given blog.
  *
- * @since MU
+ * @since MU 1.1
+ * @uses get_blogs_of_user()
  *
- * @param int $blog_id Blog ID
- * @return bool True if the current users belong to $blog_id, false if not.
+ * @param int $user_id The unique ID of the user
+ * @param int $blog Optional. If no blog_id is provided, current site is used
+ * @return bool
  */
-function is_blog_user( $blog_id = 0 ) {
-	global $wpdb;
+function is_user_member_of_blog( $user_id = 0, $blog_id = 0 ) {
+	$user_id = (int) $user_id;
+	$blog_id = (int) $blog_id;
 
-	if ( ! $blog_id )
+	if ( empty( $user_id ) )
+		$user_id = get_current_user_id();
+
+	if ( empty( $blog_id ) ) {
+		global $wpdb;
 		$blog_id = $wpdb->blogid;
+	}
 
-	$blogs = get_blogs_of_user( get_current_user_id() );
-
-	return is_array( $blogs ) && array_key_exists( $blog_id, $blogs );
+	$blogs = get_blogs_of_user( $user_id );
+	if ( is_array( $blogs ) )
+		return array_key_exists( $blog_id, $blogs );
+	else
+		return false;
 }
 
 /**