It is a drumming VSTi. I've just started using it, seems absolutely awesome. Of course can program the drum beats from scratch, but what makes this one special is that you can turn it to "Jam" mode, and it will play along with your live keys/guitar live (or your audio or MIDI tracks)!! And if you don't quite like the first Jam session, replay, and it will give you a new one!
They have some good video and demos on their website, rayzoon.com I believe, yes I just confirmed it.
They have programmed the "styles" of several famous Drummers - John Bonham, Stewart Copeland (Police), and so what the machine will drum will be (theoretically) in the specific style you choose. I have asked for Ringo drummers to be programmed! (Nothing yet :-( )
Anyone else have experience with it? I'm just starting out, though some years ago I used an earlier version.