There's a free one and a paid one. I want to give it a try, but even though they say they've got AU/VST/RTAS, the current installer only contains VST.
I quickly heard back from Two Notes, and the nice lady told me that the AU version will be available this week. I'm really looking forward to checking it out. If it works, I'll buy the paid version. Gee, it's almost as if they're giving the free version away, to get people hooked!