According to this blog post:
"In the recent event Google Developers Day, Bangalore, the Keynote speaker Prasad Ram said that Google Appengine will now support Java. [...] "Java", said the other speaker, "was chosen based on the community feedback."
Splendid! I hope this includes Scala somehow. This would at last be an easy way to deploy Java web applications, one thing up to now only PHP could claim (and to a lesser amount Ruby and Python).