I've written about Banksy a few times. There is something about artful vandalism that is appealing.
Advertising posters at New York city subway stations are undergoing artful vandalism by a mysterious artist called Poster Boy NYC.
You can see more of his art here (flickr), read an interview with him by Marissa Neave, and a write up by Brian Raftery in NY Mag.
(Photo: Christopher Anderson) in NY Mag
Defacement of public (or private) property = vandalism, or art?