Pidgin has introduced a major update with version 2.6.0, and the current bug-fixing 2.6.1, and along with more than 100 fixes between the two comes support for Google Voice and Google Talk. If you're on Windows, though, this won't mean much--the protocol currently only works with XMPP at the moment, not the derivative protocol that Google uses. Pidgin Portable 2.6.1 is also available for USB keys.

More: http://download.cnet.com/8301-2007_4-10313556-12.html