Trillian Astra, the next version of the popular Windows multi-client chat application Trillian, is being developed for the Mac. Cerulean Studios, the makers of Trillian, has released a limited and experimental Mac version to approved testers of their new Astra platform. Hopefully a working version will be made available for general release someday; Astra itself as been in invite-only Alpha stage for nearly a full year now.
Trillian on Mac is something that many people have waited for for a long time. It's an aesthetically pleasing, feature rich service with a very loyal group of users. Trillian Astra users can chat seamlessly with friends on Yahoo!, ICQ, AIM, Bonjour, Windows Live, Google Talk and MySpace IM. There's a web component of the new service, an RSS ticker and more - see a screenshot of the pared down Mac version below.
The particulars of this service as opposed to others are better experienced than they are described. Other multi-client chat tools include the open source Pidgin (formerly known as GAIM) on Windows and Adium on Mac.
See a screenshot of the current Mac build below the fold.