Windows Live Messenger - talk to Yahoo! contacts

Yahoo! & Microsoft have joined forces. Now you can use Windows Live Messenger to talk to your friends who use Yahoo! You’ll be able to see when Yahoo! users are online and communicate with them from Windows Live Messenger. Visit the Microsoft website HERE.

The beta program is filled to the brim at the moment. Join the waiting list and we'll notify you the moment things open back up. Visit the Yahoo! website HERE.

But those of you that read my "What Is Gaim?" blog are already doing this.

Google Talk :
Now that Google has opened up their Google Talk servers for federation with other Jabber servers, you can use Google Talk to connect to your friends on AIM, MSN, Yahoo or ICQ.
Here's how, with step-by-step instructions [and screenshots].