Motion 2 (debuted yesterday) could be a solution for Video Jockeys who don’t want to pay for extra software (like I did with Arkaos). “MIDI support allows Motion 2 to be “played” like a musical instrument with animation changes triggered by playing a keyboard or using faders or knobs on a MIDI controller.” Link
Motion 2 and VJs
Looks cool, but it’s USD$299 and you need a dual processor G5 with 4gig of ram to run it properly. ArKaos is stil looking like a better option to me.