Also claims to be the source of this photo.
Read the comments. These signs are appearing in numerous locations around LA
"The Eastsider is not going to touch this one. The question comes from A Friend of The Eastsider who recently snapped this photo of photographer Gary Leonard taking a photo of a sign painted on those easy-to-clean walls of artist Shepard Fairey's Echo Park studio. The sign reads "Acorn Funded Prostitution Zone." Since Fairey is not likely to respond to any questions, all theories are welcome. Posted by The Eastsider LA at 12:00 PM Labels: Dear Eastsider, Echo Park, Shepard Fairey"
http://www.theeastsiderla.com/2009/09/dear-eastsider-whats-deal-with-acorn.html
Thanks for the link. The comments there are pretty interesting.