As of today, Jabba will play in the Playchess engine room for a while.
It's an attemt to start getting some more amatuer engines playing there... at the moment, it's just full of people using Rybka and Stockfish.
The interface is really nice, and there is a lot of potential.
Jabba also plays on the ICC.... under the handle JabbaC.
Playchess handle is Jabba_Engine