Rollback awareness.

Tasks are aware if they are in rollbacks; they will be invoked only if
they implement the new interface RollbackAware.

docs/example-config/.mage/tasks/SampleTask.php

@@ -0,0 +1,14 @@
+<?php
+class Task_SampleTask
+    extends Mage_Task_TaskAbstract
+{
+    public function getName()
+    {
+        return 'A Sample Task';
+    }
+
+    public function run()
+    {       
+        return true;
+    }
+}