I flipped the switch to connect the Google Talk Service to the public XMPP network this morning. Google Talk users can now chat with users on other XMPP services and vice versa.
If you want to connect your service to the Google Talk Service, you should know that Google Talk uses the dialback protocol as described in RFC 3920.
Please post to the Google Talk Open Group if you have any questions or problems with interoperability on the Google Talk Service.
I'm proud to have worked on this, and to be the one that got to turn on something that lets Google Talk users talk to millions of other users out there.