Google today announced that they will be supporting Java on their GAE cloud computing platform. I signed up for the beta, but don’t know when/if I’ll be approved.
I also saw that the platform also now includes a cron mechanism to run scheduled “jobs”, see: http://code.google.com/appengine/docs/python/config/cron.html
This could change things. It will be interesting to see how (if?) Amazon responds.