So far, the only thing that Adobe has released for the Mac is in Beta form at the moment...or maybe it's been released since they put out the latest Creative Suite Bundle.
It's called Soundbooth. Seems like it's going to be kinda counter-intuitive...and I don't think it's supposed to be available as a separate piece of software...
But, you can go to the adobe website and check out the info on it.
Other than that, I haven't heard anything about cross-platform versions of Audition.
Check out Soundbooth though...might be cool...