First, there's is a sort of code of conduct where artists shouldn't cover up another artist's work. There's a wall on N 5th St in Williamsburg that has some work by FAILE. This work has been there for at least a year.
Another aspect is where's the audience you're trying to reach. When I moved to Willaimsburg over 10 years ago there wasn't much street art. When I moved out about 4 years ago, there was much much more and it had also spread further out. More artists were living in the area. Other artists from afar were posting in that area because they wanted to be seen by this audience. And work spread radially as rents went up. I was back in the neighborhood a few weeks ago and I found that certain areas were totally blanketed: http://bit.ly/hiAL6
Having recently moved out to Jersey City, I've noticed the growth of street art (including graffiti) as the art and hipster crowd has grown.
Wooster Collective has an interesting thread about this on their Facebook page: http://bit.ly/MthKD
As @painkillas noted, there's also not a common agreement on what street art is. Wooster also has an interesting thread there too: http://bit.ly/wn5mc
btw: I like what you've done with Street Art News]]>
oh, re: painkillas: I see streetart as a creative expression. it makes inner city living more vibrant. I guess there are many perspectives though.]]>
and graffiti is just a symptom of crime and poverty. i wouldn't want to see that.]]>