There is no public API for checking the status of tasks. A task is really nothing more than a normal http request which is monitored by GAE to retry it if it fails. The real brains is in the task queue which is simply a queue of URL's that app engine will fire off at a given rate and retry failed requests. The only public method to check tasks (http requests) in this queue is the console webpage. Its up to you to monitor your tasks yourself by storing some kind of status data in memcache or the datastore.
