Adium

Preferred license: GNU General Public License (GPL)
Adium is an messaging application for Mac OS X that can connect to AIM, MSN, Jabber, Yahoo, and more. The Adium project is a loosely organized group of volunteers that handles almost everything related to developing, distributing, and supporting the application.
 
Current Projects
by Branton John Homer, mentored by Peter Hosey
by Geoffrey Foster, mentored by David Smith