From the Gaim site:
I (Sean) have been hired by Google, moved to Seattle, and have been working on the Google Talk team for about a month and a half. The goal of Google Talk is to make real-time communication as open as possible, and in that regard, I’ve been working to offer all of Google Talk’s features into other clients. Currently, I’m working on making it as easy as possible for other clients to use Google Talk’s voice features. You can expect Gaim and other clients to be interoperable with Google Talk’s voice features in the near future.
Good, maybe they could start by documenting the protocol and let us all help out.