Related link: http://simile.mit.edu/java-firefox-extension/
I admit I haven’t had quite enough time to put it through the motions. However, I intend to give it the good ole college try on seeing how this relates to XULRunner in terms of development. If it is possible to build business layer in Java and UI in XULRunner, this might represent something extremely cool in terms of desktop app development. Honestly, I still wish the JRE would include Gecko/XUL out of the box, but barring that, this seems like a pretty nice balance between the two.