This Spring, at the University of Washington's Technical Communications Lecture Series, a Microsoft researcher showed us some interesting experiments they were conducting with interfaces projected on walls, touch screens projected on tables and using hands and lasers instead of mice to point and click.

I just came across this video link on the IxDA discussion board that that takes this technology out of the lab and promises a new way of interacting with computers and software.

Naturally, this has been in development for awhile. Alex Wexelblat pointed out that the military was experimenting with touch screens and found them "highly error prone and fatiguing"
Error sources include:
- size of the pointing device (fingertip vs cursor)
- selection with the finger obscures the thing you're trying to select
- uncertainty on feedback. The combination of physical feedback (does
the screen flex in response to pressure? If so how much and how does
the user correlate that feedback with visual changes?) proved
difficult for some users.
- dirt and oils from human hands tended to introduce errors and
- obscure displays after extended use

I've also read several other accounts of touch screens not performing well in industrial settings and in police vehicles. In these case it was as much a usability issue with the software as the touch screen hardware. In both cases no field studies were done to see how these systems would function in real-world situations.

What you'll see on the video is miles ahead of what we're used to seeing in today's touch screens.

It would be interesting to see just how "intuitive" user's would find this no-interface-interface.