I was just watching these videos http://www.multitouchmusic.com/software-2/touchlive/
and I realised that making a touch interface for very large screens is a challenge because it then becomes difficult to use multiple fingers when interface elements are too far away.
In this person's case the sliders and buttons would have to be made smaller which is quite different from designing interfaces for tablets where people always want things to be bigger and less cramped.

BTW: I'd love to try this app on a 10 or 11" Win8 tablet http://www.multitouchmusic.com/software-2/yeco/