Reports out of a Google developer conference in India indicated that Google was primed to add support for Java programs running on its presently Python-only. Java support is a top request for the Web application hosting site, but fans would be better off holding their horses for now.
The reports based the Java-on-GAE conclusion on remarks from a speech by Prasad Ram, director of Google research and development in Bangalore. Google, though, said nothing is happening soon.
Some, too, but it's an unofficial project.