It seemed to me that getting a java version for the plug was unnecessarily difficult for the plug. There is a Sun embedded version that's available in a trial version that seems to work fine. But I think it's only good for 90 days before you have to purchase it.
I decided to build a version of OpenJdk 7 for the plug. This version requires "libffi". It should also support GUI functionality if you have a recent version of X installed.
If you extract openjdk7-7b86-armv5tel.txz in / it will create /opt/openjdk7. It takes 134 Megs of disk so it's probably only practical if you have root on SD or USB.
If you extract openjre7-7b86-armv5tel.txz in / it will create /opt/openjre7. It takes 76 Megs of disk.
http://sheeva.with-linux.com/sheeva/index.php?dir=javaThe .tzx files require xz-utils to extract.
Hopefully this will help those of you who want to run java on the plug.