This is done by the Graffiti Research Lab
They do ‘geek graffiti’ using projectors and magnetic led banners and stuff. Is good and cool. There are lots of example on their website.
they seem to consider it a form of civil disobedience, protest and political resistance. I think it is a bit, but not really. I think they have had something to do with the Aqua Teen Hunger Force advertising thing in Boston, or at least influenced it.
it is interesting how easily civil disobedience is co-opted by advertising: