Index: wp-includes/nav-menu.php
===================================================================
--- wp-includes/nav-menu.php	(revision 18444)
+++ wp-includes/nav-menu.php	(working copy)
@@ -580,7 +580,7 @@
 			if ( 'post_type' == $menu_item->type ) {
 				$object = get_post_type_object( $menu_item->object );
 				if ( $object ) {
-					$menu_item->type_label = $object->labels->singular_name;
+					$menu_item->type_label = $object->labels->nav_menu_item;
 				} else {
 					$menu_item->type_label = $menu_item->object;
 					$menu_item->_invalid = true;
@@ -595,7 +595,7 @@
 			} elseif ( 'taxonomy' == $menu_item->type ) {
 				$object = get_taxonomy( $menu_item->object );
 				if ( $object ) {
-					$menu_item->type_label = $object->labels->singular_name;
+					$menu_item->type_label = $object->labels->nav_menu_item;
 				} else {
 					$menu_item->type_label = $menu_item->object;
 					$menu_item->_invalid = true;
@@ -630,7 +630,7 @@
 
 			$object = get_post_type_object( $menu_item->post_type );
 			$menu_item->object = $object->name;
-			$menu_item->type_label = $object->labels->singular_name;
+			$menu_item->type_label = $object->labels->nav_menu_item;
 
 			$menu_item->title = $menu_item->post_title;
 			$menu_item->url = get_permalink( $menu_item->ID );
@@ -651,7 +651,7 @@
 
 		$object = get_taxonomy( $menu_item->taxonomy );
 		$menu_item->object = $object->name;
-		$menu_item->type_label = $object->labels->singular_name;
+		$menu_item->type_label = $object->labels->nav_menu_item;
 
 		$menu_item->title = $menu_item->name;
 		$menu_item->url = get_term_link( $menu_item, $menu_item->taxonomy );
Index: wp-includes/post.php
===================================================================
--- wp-includes/post.php	(revision 18444)
+++ wp-includes/post.php	(working copy)
@@ -1176,6 +1176,7 @@
 	$nohier_vs_hier_defaults = array(
 		'name' => array( _x('Posts', 'post type general name'), _x('Pages', 'post type general name') ),
 		'singular_name' => array( _x('Post', 'post type singular name'), _x('Page', 'post type singular name') ),
+		'nav_menu_item' => array( _x('Post', 'menu item type'), _x('Page', 'menu item type') ),
 		'add_new' => array( _x('Add New', 'post'), _x('Add New', 'page') ),
 		'add_new_item' => array( __('Add New Post'), __('Add New Page') ),
 		'edit_item' => array( __('Edit Post'), __('Edit Page') ),
Index: wp-includes/taxonomy.php
===================================================================
--- wp-includes/taxonomy.php	(revision 18444)
+++ wp-includes/taxonomy.php	(working copy)
@@ -398,6 +398,7 @@
 	$nohier_vs_hier_defaults = array(
 		'name' => array( _x( 'Post Tags', 'taxonomy general name' ), _x( 'Categories', 'taxonomy general name' ) ),
 		'singular_name' => array( _x( 'Post Tag', 'taxonomy singular name' ), _x( 'Category', 'taxonomy singular name' ) ),
+		'nav_menu_item' => array( _x('Post Tag', 'menu item type'), _x('Category', 'menu item type') ),
 		'search_items' => array( __( 'Search Tags' ), __( 'Search Categories' ) ),
 		'popular_items' => array( __( 'Popular Tags' ), null ),
 		'all_items' => array( __( 'All Tags' ), __( 'All Categories' ) ),