I'm not much of a hardware hacker but this looks like a pretty small DIY project. A tighter, nicer package might be nice but I think the point is that the ``commercialized" version (cf. Microsoft Surface) is really expensive.
Even commercialized, this could be a cheaper and more versatile version of electronic whiteboards. Just bundle a portable LCD projector and an infrared sensor together and include software so it just works. Get a good team together and apply to Y Combinator.
I agree. I've done some research on how to develop all kind of Microsoft Surface related stuff, and no doubt there are a lot of alternatives to create a similar effect in a much cheaper way. However, I haven't seen anything this versatile... this idea and implementation is absolutely fantastic.