This app releases March 20th and if it includes the american locations of Graffiti this is going to be cool. No matter what town your in you can take a tour of the urban art and graffiti right from your iPhone. It looks like it's sponsored by Adidas too. This would be real cool if you could take a pic upload it and the GPS location and then download the map of the city your in and take the tour.
http://urbanartguide.com/