First, the links so you can check it out.
http://www.google.com/talk/
So it's basically an MSN Messenger replica. Tells you how much mail is in your gmail box, Instant Messaging, and Voice Chat.
Now, my buddy thinks that no one will use it because everyone already has their Yahoo clients or MSN Messenger etc, and no one will switch.
Personally I think everyone will have in 12 months or less.
Place your vote NOW!