That is an unbelievably cool idea; it's a shame that it can only be played at live events but you can kind of see why. :L
Really cool to see some crazy innovations like this cropping up; though it might be better if we could get away with some in standard games that don't require a cellist.
Thank you for making me have an epiphany: A game where you control the tank and there's a music track playing and "controling" the turrets. Difficulty would change depending on tempo, notes and the melody. Downloadable songs via PSN and XBL. It could actually work.
OT: this looks pretty cool. I wonder if it could be applied to any instrument?