Does anyone know if Graffitio is still around?

I went back and listened to Giant Bombcast 08-12-2008 and one of the Listener questions was about Iphone apps. Ryan talked about an app called Graffitio (I am not sure on the spelling). It was an app in which you could make virtual walls and people within a certain radius around the location of the wall could "tag" it and leave graffiti and messages. I can't find it in the app store. Does anyone know if this app is still around, or if it is under a new name?