gistfile1.php

function wp_get_associated_nav_menu_items( $object_id = 0, $object_type = 'post_type' ) {
	$object_id = (int) $object_id;
	$menu_item_ids = array();

	$query = new WP_Query;
	$menu_items = $query->query(
		array(
			'meta_key' => '_menu_item_object_id',
			'meta_value' => $object_id,
			'post_status' => 'any',
			'post_type' => 'nav_menu_item',
			'showposts' => -1,
		)
	);
	foreach( (array) $menu_items as $menu_item ) {
		if ( isset( $menu_item->ID ) && is_nav_menu_item( $menu_item->ID ) ) {
			if ( get_post_meta( $menu_item->ID, '_menu_item_type', true ) != $object_type )
				continue;

			$menu_item_ids[] = (int) $menu_item->ID;
		}
	}

	return array_unique( $menu_item_ids );
}