I have a few comments:
1. I hate to be the negative one, but there are many people who are more knowlegable in patents than I, and they feel that this is an effort by Apple to corner a new section of the market before it is even created. This patent is is no way indicative that Apple actually has this technology.
2. If they do, as I hope, its not going to be applied (at first) in a non-functional, decorative way. Imagine being able to receive status signals directly from your tower, such as the ones on a car's instrument panel. There could be projections of system load, core temperature, volume and brightness. And within a rack of xServes, an individual server which encounters an error can change its panel red. There are many useful applications for this technology, and I doubt it will be used in a mood ring/visualizer way, when Apple can hardly get the iTunes visualizer to run with decent speed on a normal screen.
3. One of the most orignal ideas I've heard on the boards involved the iPod's lucite front. Subtract the screen and controls and you could project the controls, information, and a small visualizer when non in use. It might subtract some of the funcationality of the scroll wheel, but it would be a creative step forward nonetheless.
I think we must be postitive about this, while keeping in mind that this technology may not even be advanced/exist.