Fire is a Mac OS X multiprotocal IM client. It's rather great in my opinion.
This feed will give you the latest information on the 2.0 beta build that is available for downloading and compiling from their site.
See http://fire.sourceforge.net/development/developer.php for instructions on how to do that. See http://fire.sourceforge.net/forums/index.php?sid=289cc58e00ed35ea739c3d7af700fcf5 for information on Fire, reporting bugs and so forth.