There was a nice bit of kit featured on the Guardian’s Dork Talk page recently. It was the LaserKey CL850 Projection Keyboard, a device that projects a virtual keyboard onto your desk and uses light sensors to detect which ‘keys’ your fingers are tapping.
It’s a bit of sci-fi wizardary come to life.
The device is aimed at the handheld technology market and communicates with your PDA or Blackberry via Bluetooth or USB. This would be a great tool for people like me who find using tiny fiddly, plastic buttons to type anything bigger than a simple text message a bit of a nightmare. It would also enable mobile communication and learning to be taken to the next level – increased accessibility, accuracy and speed for typing on screen.
The only downer about this product is that it’s yet another additional bit of hardware that you need to carry around with you along with your mobile device. If your Blackberry itself could beam out the keyboard then we’d truely be in sci-fi business heaven.
Jonny Crook 
This has been around for ages and was aimed as a replacement for normal computer keyboard. Which failed.
The “Human Computer Interface” is the challengefr mobile devices – I’ve been meaning to order one of these as a test for ages.
The keyboard is for me the most useful interface but device “senses” are developing.
Many are lookign beyond the reign of the mouse – devices that can sense you in more ways – motion, audio and visual etc.
Still I think we might see more projected interfaces like this