Jax is a Java developer conference focusing on enterprise, mobile, web, open source, tools, methodologies and implementation. About 250 people attend. Last year this event was sponsored by Red Hat/JBoss but I don't know if they are sponsoring it this year. Dan Allen (mojavelinux) will be there giving several talks as well as judging the JAX innovation awards which will be announced at the conference.

http://fedoraproject.org/wiki/Jax_US_2012