--- taxonomy.v1.340.module	2007-02-24 11:21:43.281569400 +0100
+++ taxonomy.module	2007-02-24 11:26:39.955343100 +0100
@@ -1264,6 +1264,8 @@ function taxonomy_render_nodes($result) 
     $output .= theme('pager', NULL, variable_get('default_nodes_main', 10), 0);
   }
   else {
+    // remove (outdated) terms without content from search engines
+    drupal_set_header('HTTP/1.0 404 Not Found');
     $output .= '<p>'. t('There are currently no posts in this category.') .'</p>';
   }
   return $output;