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/
Update: The artists who created these are Scribe (characters), Emit and the ATT guys
I was in Kansas City this weekend and I wanted to check out the graff scene there. They have some excellent artists that really get up in the downtown area. I took these pics I'm not sure who all these artists are but if you see your stuff here drop me a line in the comments and I'll credit you, nice work. Check out the pics: A few more that Lauren took: