That's pretty cool, and a much better interface than some of the other desktop metaphor interfaces (being that you can really see what you're doing).
That said, frankly I don't see this being all that useful for a lot of users in the near term.
Certainly, if I'm writing code, I don't want to even take my hands off the keyboard, let alone be waving both of them around a lot--try that for 16 hours a day and every geek will have biceps like Hulk Hogan.
But it shows tremendous potential for creative and scientific fields where multiple people are working together on a shared viewspace--instead of using a whiteboard or projection screen from your laptop, you can just walk up and interact with the screen.
Photographers could end up liking it, filmmakers (particularly storyboard and such) could benefit majorly, and many scientific fields could do well with this. Classrooms too, in theory, although that'd be spendy for most schools.
But I'll venture a guess and say it's overkill for a lot of "home" systems. Heck, if single-touch screens were really THAT much more productive than a mouse and keyboard, everybody would buy tablet PCs. Multi-touch helps, but it's still not ideal for everything regardless of how cool it looks.