Regine has an intriguing post on her excellent blog about grafedia a project kicked of by John Geraci. Unlike similar projects like yellow arrow or urban tapestries the point is less about adding an information overlay of annotations or memories to a city and is more freeform -- like grafitti. Ostensibly you could link up to an array of media tapes (video, images, audio) about anything. Add meaning, detract meaning, obfuscate meaning.