diff --git a/wp-admin/nav-menus.php b/wp-admin/nav-menus.php
index 31123f6cdf..7bbf1e8401 100644
--- a/wp-admin/nav-menus.php
+++ b/wp-admin/nav-menus.php
@@ -482,7 +482,18 @@ require_once( 'admin-header.php' );
 									<input name="menu-name" id="menu-name" type="text" class="menu-name regular-text menu-item-textbox input-with-default-title" title="Enter menu name here." value="<?php echo esc_attr( $nav_menu_selected_title  ); ?>" />
 									<br class="clear" />
 								</label>
-
+								<?php if ( ! empty( $nav_menu_selected_id ) && $slots = get_registered_nav_menus() ) : ?>
+								<label class="menu-name-label howto open-label" for="menu-slot">
+									<span><?php _e('Theme Menu'); ?></span>
+									<select id="menu-slot" name="menu-slot">
+									<?php foreach ( $slots as $slot_key => $slot_text ) {
+										echo '<option value="' . esc_attr($slot_key) . '">' . esc_html($slot_text) . '</option>';
+									}
+									?>
+									</select>
+									<br class="clear" />
+								</label>
+								<?php endif; ?>
 								<div class="publishing-action">
 									<input class="button-primary" name="save_menu" type="submit" value="<?php empty($nav_menu_selected_id) ? esc_attr_e('Create Menu') : esc_attr_e('Save Menu'); ?>" />
 								</div><!--END .publishing-action-->
diff --git a/wp-content/themes/twentyten/functions.php b/wp-content/themes/twentyten/functions.php
index 06b44d0ea5..67bb4edd02 100644
--- a/wp-content/themes/twentyten/functions.php
+++ b/wp-content/themes/twentyten/functions.php
@@ -80,7 +80,7 @@ function twentyten_setup() {
 	add_theme_support( 'post-thumbnails' );
 
 	// This theme uses wp_nav_menu()
-	add_theme_support( 'nav-menus' );
+	register_nav_menus( array('main' => __('Main Menu')) );
 
 	// Add default posts and comments RSS feed links to head
 	add_theme_support( 'automatic-feed-links' );
diff --git a/wp-content/themes/twentyten/header.php b/wp-content/themes/twentyten/header.php
index 97f743e238..c789ddc747 100644
--- a/wp-content/themes/twentyten/header.php
+++ b/wp-content/themes/twentyten/header.php
@@ -69,7 +69,7 @@
 
 			<div id="access" role="navigation">
 				<div class="skip-link screen-reader-text"><a href="#content" title="<?php esc_attr_e( 'Skip to content', 'twentyten' ); ?>"><?php _e( 'Skip to content', 'twentyten' ); ?></a></div>
-				<?php wp_nav_menu( array( 'sort_column' => 'menu_order', 'container_class' => 'menu-header' ) ); ?>
+				<?php wp_nav_menu( array( 'sort_column' => 'menu_order', 'container_class' => 'menu-header', 'theme_menu' => 'main' ) ); ?>
 			</div><!-- #access -->
 		</div><!-- #masthead -->
 	</div><!-- #header -->
diff --git a/wp-includes/nav-menu-template.php b/wp-includes/nav-menu-template.php
index 52cefa243c..f73e90c603 100644
--- a/wp-includes/nav-menu-template.php
+++ b/wp-includes/nav-menu-template.php
@@ -193,7 +193,7 @@ class Walker_Nav_Menu_Checklist extends Walker_Nav_Menu  {
 function wp_nav_menu( $args = array() ) {
 	$defaults = array( 'menu' => '', 'container' => 'div', 'container_class' => '', 'menu_class' => 'menu', 'echo' => true,
 	'fallback_cb' => 'wp_page_menu', 'before' => '', 'after' => '', 'link_before' => '', 'link_after' => '',
-	'depth' => 0, 'walker' => '', 'context' => 'frontend' );
+	'depth' => 0, 'walker' => '', 'context' => 'frontend', 'theme_menu' => '' );
 
 	$args = wp_parse_args( $args, $defaults );
 	$args = apply_filters( 'wp_nav_menu_args', $args );
@@ -202,6 +202,12 @@ function wp_nav_menu( $args = array() ) {
 	// Get the nav menu
 	$menu = wp_get_nav_menu_object( $args->menu );
 
+	if ( ! $menu && $slot ) {
+		$slots = get_nav_menu_slots();
+		if ( isset($slots) && isset($slots['theme_menu']) )
+			$menu = wp_get_nav_menu_object( $slots['theme_menu'] );
+	}
+
 	// If we couldn't find a menu based off the menu argument 
 	// get the first menu that has items.
 	if ( ! $menu ) {
diff --git a/wp-includes/nav-menu.php b/wp-includes/nav-menu.php
index c087f3ff3c..2a6cdd9e28 100644
--- a/wp-includes/nav-menu.php
+++ b/wp-includes/nav-menu.php
@@ -61,6 +61,31 @@ function is_nav_menu( $menu ) {
 	return false;
 }
 
+/**
+ * Register nav menus for a theme.
+ *
+ * @since 3.0.0
+ *
+ * @param array Associative array of menu slot identifiers and descriptions.
+ */
+function register_nav_menus( $menus = array() ) {
+	global $_wp_registered_nav_menus;
+
+	add_theme_support( 'nav-menus' );
+
+	$_wp_registered_nav_menus = $menus;
+}
+
+function get_registered_nav_menus() {
+	global $_wp_registered_nav_menus;
+
+	return $_wp_registered_nav_menus;
+}
+
+function get_nav_menu_slots() {
+	return get_theme_mod('nav_menu_slots');
+}
+
 /**
  * Determine whether the given ID is a nav menu item.
  *