I've used it every day for a month and have had no such problem. Adium, by design, does not scroll to the bottom if you're not already scrolled to the bottom (so that new messages don't mess with you trying to read old messages).

Make sure you're scrolled all the way to the bottom and new messages should automatically scroll down.

It (Adium's WebKit) does support some animation stuff, but the current system is lacking any solid event notification to really do all the fun little things I wanted to do. I've discussed this with some of the others in the #adium/-dev chatrooms, and even submitted a pull request to add an event for when anything happens (but it could still be better). I haven't heard anything from anyone regarding the pull request.

That being said, I've had the code up on GitHub since the beggining: https://github.com/CWSpear/hangouts-ad...ssage-style (don't forget to minify the JS!). Just don't get too carried away with any animation stuff: remember I'm in some chatrooms that get 1000s of messages a day, and I don't usually restart Adium for weeks! (Hence my release today, btw...)