On tagging, bombing, etc
I'm personally divided on spraycan art. On the one hand, I appreciate the aesthetics and anarchic bent of graffiti. Graffiti is great because of the restraint placed by the medium, and that uses the city as a canvas and isn't hidden behind gallery doors. At the same time, I understand that it does deface public and private property, and let's face it, for every great work, you get a dozen ugly scrawls.
No, I'm not against going after writers per se - the art thrives partly because of the cat-and-mouse game - but I do have an issue with thinking of graf as invitation to crime or social disorder, and that stopping writers will somehow get rid of whatever motivated them to start writing in the first place.
I simply bring this up because, for whatever reason, there's quite a bit on street art in the old internets, from Mayor Bloomy's crackdown on graf (Gothamist), a piece in my favorite Canadian culture mag, Maisonneauve, The City as Canvas: Graffiti and Stencil Art from New York to Montreal, and some cool tags on Cityrag.
Also check out @149st and the wonderful 1983 documentary Style Wars.