This is a beautiful and interesting concept, but isn't this really just a dressed up command line interface? This is a feature I would absolutely love to have, but I don't see it replacing the menu in the form demoed for the simple reason that this violates one of the core principles of user-centered design: visibility. If the user has no visual indication of what is possible within the system, how can we expect them to learn the interface?

One super simple example of this: http://cl.ly/082D441E2D0L1l3d3g2Y

Most readers of Hacker News are probably aware of the calculator feature in the Spotlight in Mac OSX, but if I had a dollar for every time I've blown someone's mind by showing it to them, I'd be counting money right now rather than writing this comment. The bottom line is, visibility is an extremely important design principle, because it informs the user what they can do within a system, so hiding possibilities is probably not a good idea.

For detailed reading on the principle of visibility, check out Donald Norman's Phenomenal The Design of Everyday Things, which I firmly believe should be required reading for anyone thinking about building anything: http://www.amazon.com/gp/product/0385267746/ref=as_li_ss_tl?... [yes, it is an affiliate link]