here and there you can see that google is launching a IM service (at least!).
It has been rumored for such a long time...
This is really great because they are using XMPP/Jabber underneath.
I'm already connected to their Jabber servers using my client (AdiumX).
At least for now I'm not able to connect my own jabber server to theirs (using S2S - Server to Server connection) I hope this is only a temporary situation, and that'll change when they will release talk.google.com (and their associated client).
If you want to test the IM service, drop me an instant message at my gmail address (first name dot last name @ gmail.com)