Wired magazine has an article on Lichtfaktor, a Cologne based art duo, who use fast moving light sources and long-exposure shots to create fantastic, animated graffiti art.
Though this is not a new technique, Lichtfaktor have managed to turn their ‘Light Scribing‘ into a commercially viable art form. Various companies like Philips and Current TV have used their imagery for their ad campaigns.
Link to Lichtfaktor’s official site and gallery. Visit LichtFaktor’s Flickr stream to see the images in higher resolutions.
If you are interested in learning this technique, visit here, here and here for more. All you need is a decent digital camera and lots of patience.