Chat Core (part of the Colloquy project) is a BSD licensed open source ObjC IRC and SILC framework.
Cool, I think this'll come in handy� �DustinVoss
Proteus also has its chat services available, although I know nothing about them.
Proteus's imservices is a daemon for insulation from the GPL. It used to incorporate libfaim (AIM-TOC), libfiretalk (AIM-OSCAR), libgg (Gadu-Gadu), libicq2000, libjabber, libyahoo, libyahoo2, msnlib, and Proton's Proteus Plugin (which was RendezVous Plugin for Proteus before TIBCO's lawyers heard of it); version 4 uses libgaim, presumably replacing most of the above. The source is supposed to be available at indigofield.com via SubVersion and ViewCVS, neither of which I've ever seen working.
A backup copy of Acid, a jabber library written in Cocoa is available here (since it isn't hosted on jabberstudio.org anymore) http://code.kluivers.nl/wsvn/Projects/Acid/trunk/#/Acid/trunk/