We've been getting parts in for our large scale multi-touch wall project and I have to say it's like Christmas all over again. Cameras, lenses, filters, projectors, and... well lasers! Sweet. And not those wimpy 5 mW ones, these are 60 mW ones.
For multi-touch you use infra-red light, so these are infra-red lasers. I had to fight the urge to just plug them in and see a massively powerful beam of light since they're invisible. That makes safety even more important since your body doesn't have the natural reaction to blink if you accidentally shine them into an eye.
Can't wait for the safety goggles to arrive so we can actually play with them.