On the 14th Trillian Astra, Cerulean Studios’ multi-protocol IM client, finally left beta and is now available in a free and pro version ($25). I have been using Trillian Astra since alpha and it’s definitively my favorite IM client, especially since Digsby joined the dark side. See the Lifehacker post for more details.
Trillian Astra allows you to chat using the following services: Windows Live, Yahoo!, MySpaceIM, AIM, Google Talk, ICQ, Jabber, Skype, and IRC. It also has email, Facebook, and Twitter support. I haven’t tried all protocols yet, but at least ICQ, Google Talk and Windows Live work as a charm.