Index: wp-admin/includes/update.php
===================================================================
--- wp-admin/includes/update.php	(revision 15277)
+++ wp-admin/includes/update.php	(working copy)
@@ -256,7 +256,7 @@
 		return false;
 
 	if ( current_user_can('update_core') )
-		$msg = sprintf( __('An automated WordPress update has failed to complete - <a href="%s">please attempt the update again now</a>.'), 'update-core.php' );
+		$msg = sprintf( __('An automated WordPress update has failed to complete - <a href="%s">please attempt the update again now</a>. If you update manually, don\'t forget to delete the .maintenance file located in your WordPress folder.'), 'update-core.php' );
 	else
 		$msg = __('An automated WordPress update has failed to complete! Please notify the site administrator.');