Perceptive Pixel is a leader in the development of large multi-touch screens. Multi-touch screens, for anyone unfamiliar with them, are just what they sound like: touch screens that allow users to employ multiple touch points on the screen simultaneously (and do different touch screen tasks simultaneously as well). Some of the potential advantages/opportunities this creates include:
Much faster, more efficient touch screen experiences
The facilitation of much more creative touch-screen applications
The development of simpler, cleaner, more unified interfaces (e.g. commands can be completely gestural)
Facilitation of multi-user touch-screen applications and activities
Multi-touch screens aren't new per se, but are only now really coming into their own and starting to get traction. There's a really nice demo of multi-touch screen possibilities by Perceptive Pixel founder Jeff Han from the 2006 TED conference here.