The UI won't be changing too much, but it will be modified to allow for some new features:
- Tabs - this one is huge. We all know tabs, and the team decided to go with the classic one IM window with tabs on the bottom. If you close the window, it only closes the Tab that you are currently in (which is a nice touch).
- Voice chat support - one of the most highly requested features it would seem. You can make free computer to computer calls and you can even call phones (and have a phone number associated with your Yahoo! Messenger) thanks to Yahoo! Voice.
- A new notifications section - one of the nice things about Yahoo! Messenger is that you can IM someone who isn't online and they'll get that IM when they sign on. Sadly, that means if you haven't been online in a while you can face an onslaught of windows when you start up Messenger. Tabs remedy this somewhat, but the good folks at Yahoo! went one step further and create a new section in Messenger that will show you, in your buddy list, any IMs you might have missed. You will find your voice mail here, yes you will be able to get voice mail on Yahoo! Messenger.
- Archiving - finally the next beta will offer a way for you to archive your messages, and not just in an ugly text file. It is clear that the team spent some serious time on the UI for the archives, and it shows. The archives also offer full Spotlight integration so now you can search your IMs just as easily as you can search the rest of your Mac.