I had the chance to play with one of these yesterday at the Sounds Expo in London:
http://www.jazzmutant.com/lemur_overview.phpI got to play around with it for about five minutes, and it was absolutely incredible. If you look at the top pic on the page, with the multi-colored bouncey balls, what basically occurs is that when you touch the screen, one of those balls appears for each of your fingertips. You can then flick them off in any direction, and they bounce pong-style around the screen. Once this is accomplished, you can control the speed and rotation of each bouncey ball by pressing your fingertips to the screen. The balls will act as if they're connected to your fingertips by rubber bands. You can drag them around the screen, flick them off in a different direction, whatever. You can configure them to have different amounts of friction, so they'll either bounce forever, slowly come to a halt, or stop exactly where you stop dragging your finger across the screen.
This is only one of the various UI elements, though. It has standard sliders, faders, buttons, as well as some other elements similar to the bouncey balls. The latency is essentially zero. While I was playing with it, the UI was being utilized to control various parameters in Reason. Each UI element was linked to some various parameter of an analog synth or mixer. The results were pretty insane. Easily the coolest thing I've seen in a couple of years.
The quoted price was 2000 euros. I'm too much of a slacker to do the USD conversion (plus xe.com seems to be down)