I am a web developer (J2EE application developer) and just want to expand what tools I use. I want to use Open Solaris for my personal projects. I have nothing against Linux and It looks like a lot of the same tools are on both systems.
Have you jumped to Solaris, was it a good experience?
For J2EE work per se, probably not much. As a more general developer you may appreciate DTrace. As an admin you'll love ZFS & zones. You'll hate the outdated utilities (mostly user-land) though. FreeBSD is a nice in-between Linux & Solaris though. :)