Here's an interesting article on an app for the iPhone. It demonstrates a conceptual movement called locative art, meaning art which is location dependent, enabled by technologies like GPS. Locative art is a kind of augmented reality, and relates to ubiquitous computing (computers everywhere). There's an app out where you can see the twin towers as well. The iPhone kind of makes the helmets in William Gibson's Spook Country (which I reviewed on my other blog) seem clunky before their invention.