=== modified file 'uc_node_checkout.module'
--- uc_node_checkout.module	2010-04-15 08:10:19 +0000
+++ uc_node_checkout.module	2010-04-15 08:10:30 +0000
@@ -418,6 +418,11 @@
         if (variable_get('uc_node_checkout_submit_redirect', TRUE) && !user_access('edit any '. $type .' content')) {
           $form['#redirect'] = variable_get('uc_add_item_redirect', 'cart');
         }
+  
+        $form['buttons']['cancel'] = array(
+          '#value' => l(t('Cancel'), $_SERVER['HTTP_REFERER']),
+          '#weight' => 10,
+        );
       }
     }
   }