Here's some example code in Python for talking to the GTalk servers to other GTalk-supported emails other than @gmail.com and @googlemail.com: http://snippets.dzone.com/posts/show/618

If you're connecting to talk.google.com to send the messages, you should be able to send to any logged-in user address. This feature is really important for our teams to use this tool.

So far it's very cool, though. Keep up the good work!