Believe it or not, this may be the prototype for the killer app in portable computing. It's called augmented reality and it alters how we see the world. But there's still a little work to be done.
Walk down the street, look at the world. This is reality. Now repeat, but wearing an odd-looking, bulky pair of glasses that place into your line of vision selective, relevant bits of data about the world; the data hovers in sight like virtual Post-it Notes, annotating your view. This is augmented reality. Glasses on, you glance to the right, at a vaguely familiar restaurant, and click a small button in your hand.