Google announced support for Java on their Google App Engine
Since this is a Java virtual machine running bytecode, afaik, this means I could actually write stuff in JRuby, etc., as well... There's already apparently an Eclipse plugin supporting Java for the GAE, and I hear that plugin lets you do Google Web Toolkit and App Engine development/deployment/debugging. Very interesting!
I have been playing with GAE using Python and the Django-based App Engine Patch, but it's good to know that I can now leverage Java and JVM as well.