Hello,
an update of JJack - Java bridge API for JACK has been released.
http://jjack.berlios.de/
Version 0.2 integrates much better with the JACK thread architecture.
The JACK processing-thread now itself executes Java code inside the Java virtual machine, after it has been attached to it calling AttachCurrentThread(..). (Thanks to Stéphane Letz for giving a hint about that.)
Enjoy and make noise, Jens