Google has entered into the Instant Messaging arena with the release of the PC-based "Google Talk" application. Aligned with their Gmail mail system (in many respects the same way as iChat requires a .mac or AIM user account) there does appear to be some compatibility with iChat, which Google have emphasised by developing a page showing iChat users how to connect up and communicate with Google Talk users.

It's important to emphasise that the Google Talk application is quite rudimentary at the moment, as is what Mac OS X Tiger users can do to communicate with PC users who make use of the application....only text chat is possible at this stage.

Learn about Google Talk here...
http://www.google.com/talk/about.html

The page on the Google site that explains how to set up iChat is nicely set out and shows the process required...
http://www.google.com/support/talk/bin/answer.py?answer=24076

It appears that the Google Talk client has been based on an open source Jabber standard and Google comments...
"....we're also supporting open standards and the same protocol that clients such as Trillian, GAIM and iChat do."

We may see greater functionality and compatibility come along with later versions of Google Talk. Google also comments that it "looks forward to offering support for more operating systems in the future", although it is unclear if this hints at a future Mac client or simply better compatibility. Some sites are suggestion that it does indeed hint at a Mac client.

More technical details of Google Talk can be found at...
http://www.google.com/talk/developer.html