The term "street art" [wiki] has been used to describe graffiti and other illicit urban art, but in case of Roadsworth (Peter Gibson, in real life), it has more literal meaning:

Shortly after the events of 9/11, Peter Gibson (a.k.a. Roadsworth) began a playful dialogue with the citizens of Montreal through a series of artistic interventions. Using stencils and paint, he set out to transform a crosswalk into a row of birthday candles, and double lines on the street into a zipper.

He had to face charges for over 80 counts of mischief. His art has quietly aroused the imagination of passers-by, but media reports of his arrest thrust him into the limelight. What followed was a public dialogue on art and public space. Artistic communities support Roadsworth, but in the city's eyes, he has crossed the line.

Links: Gallery at CitizenShift | Wooster Collective article | Roadsworth's MySpace page - Thanks Miniature Brainwave!