Parkour has been banned, by name, in New York City:

http://www.americanparkour.com/content/view/5704/1/

You can sign an online petition here to help out! Donations are not required, and you can exit out once you've signed:
http://www.ipetitions.com/petition/antinycparkourban/

Show your support. And more importantly, if you can help out please do! Actions speak louder than words. If you know something, someone, or anything else that can help, please use those resources.

Signed the petition.

You know a great thing would be would be for New York residents to write letters (snail mail) to their city official. Politicians listen to their voters, and generally read physical mail more often than email.

As of the 25th of August this whole debacle has been sorted out.

Article: http://www.americanparkour.com/content/view/5709/1/

Parkour was only called out by name by the one officer that approached the traceurs. There is no law and there may soon be an understanding. Read the article for more info.