I've just released a small sample application using the new EJB3 plugin for Middlegen (in cvs) to generate and test some EJB3 entity beans on JBoss4 (EJB3 Preview version).

To download go here:
http://sourceforge.net/project/showfiles.php?group_id=36044&package_id=136741&release_id=285881

For info on the EJB 3.0 Preview version of JBoss4, go here:
http://www.jboss.org/products/ejb3

I was amazed at how easy it was to develop and deploy the beans on the server. The whole sample took about 2 hours to build and assemble. The Middlegen plugin also seems to generate compliant EJB3 beans. Happy happy :)