Published on 04/25/2005
The iChat 3.0 Instant messaging (IM) that's bundled with Mac OS X Tiger allows iChat users to communicate with other IM platform, such as MSN messenger.
Some functions such as file transfer won't work, but the basic text communication will. That's a pretty good start. This is now possible because iChat uses the open IM protocol Jabber.
French site mactouch has an article that explains how to setup Jabber. (Google translated link) - via Macbidouille (French also).