Google recently expanded their app engine service to allow java in addition to python. No php or ruby support yet. Choosing java opens the door for both.
Using their pre-configured environments its actually pretty easy. Brian even figured out how to start saving stuff into the app engine data store. Good stuff.
If your interesting in playing with this, here are some links you’ll need in addition to the ones provided by Brian and friends:
Google’s docs for app engine data connector -Explains how jdo works. I’m a php guy, not a java guy. Using Brian’s example on how to write to and the docs found here, you should be able to get started reading and writing to your accounts datastore.
App engine SDK – Get the eclipse plug-in. Its got a local development server included so you can test your apps before sending them up to google. It also has a push button upload. The module can also co-exist with Zend’s PDT plug-in.
NOTE: When starting the development server, you may get an error from java the first couple of times the page loads. Just reload the page a couple of times and the error will go away.