Google App Engine gets Cron
code.google.com
code.google.com
So you can't do cron tasks which last more than 30 seconds. Too bad.
I'm looking foward to "Offline processing on App Engine: a look ahead" presentation during the Google I/O (http://code.google.com/intl/en-US/events/io/sessions.html).
Also, I am currently using the remote-api to create tasks that I run on my laptop or another server. I imagine the offline processing is pretty similar.
http://groups.google.com/group/httpmr-discuss/browse_thread/...
The release came at the perfect time for me, the day after I launched an app that requires regular update tasks to run in the background. It was a boon to simply add a yaml file to my app and not have to hack the functionality in.