I'm collecting information (or at least links) about functional programming languages on the the JVM. I'm going to intentionally leave "functional programming language" undefined here, so that people can have fun debating :).
Functional Languages
Languages and Libraries with functional features
Projects and rumours.
There has been discussion about making the jhc target the jvm. They both start with 'j', so that is hopeful.
Java itself may (soon? eventually?) support closures