Here are a couple of really interesting developments in the Graffiti world that connect to digital art. Below is a time-lapse animation of the artist Blu, from Spain, working in an abandoned space. It takes animation to a three-dimensional realm.
Also, Also Graffiti Research Lab (http://graffitiresearchlab.com) has been creating some really innovative combinations of guerilla artwork and digital media for years. Check out their work, as they enable artists to create outside the box.