He's storyboarded The Simpsons and came this close to appearing at the Academy Awards, but cultural ubiquity still hasn't translated into a definitive glimpse of Banksy. The British graffiti artist has been successfully eluding photographers for years, so why would he choose to be spotted on a water-tank in "paparazzi saturated" Southern California in the middle of the day. The Daily Mail has the pictures of "Banksy," but this isn't the first time they've unveiled his purported identity.
Could he be second-guessing his declined Oscar invitation? Probably not. He has, however, been active in SoCal recently. See, the above picture of a machine gun-wielding kid on a Westwood building, and below, of Charlie Brown with a gas canister (the guy lighting the canister is just an observer):