Recently a new version of Google Talk surfaced (22.214.171.124) that included features like avatars -- the final version (126.96.36.199) is now publicly available from http://www.google.com/talk. When you install it, a small box appears that lets you view "what's new" but as of this time it's still a dead link.
Overall, I think this new version is quite an improvement over the last publicly available release. There are no changes that I can see between 188.8.131.52 and 184.108.40.206, but I'm sure there have been a few minor bugs patched up in the newest version.
Google Talk's "What's New" page now works -- it doesn't give us any new information about the product other than what we know already.