Index: wp-includes/js/autosave.dev.js
===================================================================
--- wp-includes/js/autosave.dev.js	(revision 14032)
+++ wp-includes/js/autosave.dev.js	(working copy)
@@ -264,6 +264,8 @@
 		post_data["excerpt"] = jQuery("#excerpt").val();
 	if ( jQuery("#post_author").size() )
 		post_data["post_author"] = jQuery("#post_author").val();
+	if ( jQuery("#parent_id").val() )
+		post_data["parent_id"] = jQuery("#parent_id").val();
 	post_data["user_ID"] = jQuery("#user-id").val();
 	if ( jQuery('#auto_draft').val() == '1' )
 		post_data["auto_draft"] = '1';