Only in ../zen: node-teaser.patch
diff -urp ../zen/template.php ../zen_new/template.php
--- ../zen/template.php	2007-12-21 18:38:00.000000000 +0100
+++ ../zen_new/template.php	2007-12-22 12:46:00.000000000 +0100
@@ -258,6 +258,10 @@ function _phptemplate_variables($hook, $
         // Node is authored by current user
         $node_classes[] = 'node-mine';
       }
+       if ($vars['teaser']) {
+        // Node is displayed as teaser
+        $node_classes[] = 'node-teaser';
+      }
       // Class for node type: "node-type-page", "node-type-story", "node-type-my-custom-type", etc.
       $node_classes[] = 'node-type-'. $vars['node']->type;
       $vars['node_classes'] = implode(' ', $node_classes); // implode with spaces
diff -urp ../zen/zen.css ../zen_new/zen.css
--- ../zen/zen.css	2007-12-21 18:38:00.000000000 +0100
+++ ../zen_new/zen.css	2007-12-22 12:43:00.000000000 +0100
@@ -283,6 +283,10 @@
   .node-mine /* A node created by the current user */
   {
   }
+  
+  .node-teaser /* A node displayed as teaser */
+  {
+  }
 
   /* All nodes are given a node-type-FOO class that describes the type of
    * content that it is. If you create a new content type called