MonGooseIM 3.0.0 from Erlang Solutions is out. MonGooseIm is a messaging platform built around XMPP/Jabber.
According to Erlang Solutions, the new release has significantly improved performance and also improved OBDC support.
In the same space you can find ejabberd, iChat Server, jabberd14, jabberd2, Metronome, Isode M-Link, Openfire, Prosody, and Tigase. Check out this comparison for details on the functionality of each one.