Index: wp-admin/includes/theme.php
===================================================================
--- wp-admin/includes/theme.php	(revision 12155)
+++ wp-admin/includes/theme.php	(working copy)
@@ -138,7 +138,7 @@
 				$name = _cleanup_header_comment($name[1]);
 
 			if ( !empty( $name ) ) {
-				$page_templates[trim( $name )] = basename( $template );
+				$page_templates[trim( $name )] = str_replace(TEMPLATEPATH . '/', '', $template);
 			}
 		}
 	}