You might want to have a look here: http://java.sun.com/javase/downloads/embedded.jsp, specifically at "ARMv6 Linux - Headful".

It's as good as it's gonna get for consumer use for a while, and it isn't bad at all.

Also, you can use OpenJDK from Ubuntu or Debian (run it in chroot -- follow the instructions on getting Mer in chroot and then just 'apt-get install openjdk-6-jre')