Black Palace is a Mexican-based street art installation by the NY-based artist WK. This short doc on it's installation is pretty great unto itself.
Moose does "reverse" graffiti. He cleans away the dirt and grime to leave cool images on the newly clean surfaces. Not only does he make the world a better place to look at it, but he helps us realize how dirty the world really is (tip BoingBoing). For more info, check it out here.
I saw another installation/film of Blu's awhile back at a gallery in NYC with my family and we were blown (bluwn?) away. In that one you could see him painting the animation but this one, sans human, with the sun and clouds working as the clock, adds onto the prior one's promise.