This is great. We just turned on reserved instances for http://gri.pe (select "always on" in the billing section). It costs $9/month to keep three instances warm all the time. That's peanuts compared to saving the 10s warmup time if your traffic drops off for a minute.

Another huge item: up to 10 minutes of background processing on a single task queue callback:

  No more 30-second limit for background work - With this release, 
  we’ve significantly raised this limit for offline requests from 
  Task Queue and Cron: you can now run for up to 10 minutes without 
  interruption.

Make sure you turn on the new warmup handlers for your applications too. With this, AppEngine will deliver a request to /_ah/warmup and let it complete before serving traffic from a new instance.

XML:

  <inbound-services>
   <service>warmup</service>
  </inbound-services>

YAML:

  inbound_services:
   - warmup