I haven't seen anything along these lines since RASH, cue eyebrow raise it's exciting.
This documentary looks at the rise of the anti-graffiti vigilante. These characters try to stamp out graffiti as quickly as it goes up. Hence the question is posed "is it still graffiti if they're covering up graffiti?" I can't wait to see the feature.
Trailer is here http://www.vigilantefilm.com/ as well as other important info.
Keep an eye out.