John T. Unger, an artist and longtime commenter on Collision Detection, recently announced an intriguing art project called "American Guernica: A Call for Guerilla Public Art". He's calling upon artists nationwide to post replicas of Guernica, Picasso's famous antiwar painting, on billboards and the sides of buildings -- as in the Photoshopped example above.
I think I'm going to have a few dozen stickers of this work printed up.