Welcome to Jabber.org!
Jabber is an instant messaging System, similar to ICQ or AIM, yet far different. It is open source, absolutely free, simple, fast, extensible, modularized, cross platform, and created with the future in mind. Jabber has been designed from the ground up to serve the needs of the end user, satisfy business demands, and maintain compatibility with other messaging systems.
I like the idea of this Internet messenger tool. I wish there was something like this that repalced egroups. However I have not used it, am about to.