pidgin 2.6

Windows/Mac/Linux: Pidgin has released 2.6, catching up to the video, audio, and file transfer offerings of Google Talk, Yahoo, and others.

The big new feature in the 2.6 releases—already at a bug-fixing 2.6.1 as this is written—is video and voice chat support over XMPP, known primarily as the Jabber/Google Talk protocol.
http://pidgin.im/