Charcoal. Cool. I love the fact that Blu does his stuff on public walls with whitewash... Must take absolutely for ever. I'm pretty blown away by his films. Have you seen "Exit Through the Gift Shop?" It's a surreal documentary about street art featuring Banksy and Shepard Fairey and others... a VERY good watch.
I think it's a hilarious. I love marveling at the stupidity of the general public. The LA fucktards will buy a piece of dogshit if they think it's fashionable to do so.