I just hope they can make it look as good as Yahoo Messenger for Windows Vista.
Which is vaporware; a WPF concept developed by an outside development firm that has either been put on hold indefinitely or killed.
There better be a damn good reason it's going to take them another year, minnimum, to release Messenger 9. Yahoo IM 9 came out a few days ago, and it's pretty good. There are rumors Google Talk is being revamped with integration for multiple protocols
and tighter Gmail options. Meebo and other online IM sites are gaining (very small) traction, and Trillian Astra (online/offline client) will be done before too long.
Personally, I'd like rich text editing in messenger conversations at the least.
If they're changing the back-end as well as the client (if the Mac client is "awesome," the Windows client better be bloody good) then I can see it taking that long, but Messenger has always seemed to have long development times with regard to the features