The kind folks at the Mac BU dropped me a note announcing Messenger for Mac 7's availability. The big ticket item is full Audio/Visual conferencing support between Messenger on the Mac and on the PC. Sadly, this is only available for corporate accounts, so if you have a personal account you'll need to wait a little longer for that feature. Personal users, though, aren't entirely left out in the cold. You can now assign nicknames to contacts, search your contacts, and chat with people on your Bonjour network.
I use Messenger for corporate IM everyday, so I was excited to get by hands on this new version. Sadly, I can't seem to be able to log into my account using Messenger for Mac 7, so I'll have to take Microsoft's word on the new features.
Update: Oops, Messenger 7 does work for my corporate account because it requires Microsoft Office Communications Server 2007 (my workplace is still running 2005). Ah well, the neato new features will be mine soon enough.