Well, for those of you that don't know (which I'm assuming is most), Parkour is a discipline involving going from Point A to Point B in the most efficient manner possible, using nothing but the power of the human body. It was developed in the suburbs of Paris about 10 years ago by David Belle and Sebastian Foucan, inspired by their fathers' military obstacle course training.
It's not really a traditional sport, since their are no points involved, and no teams. And it doesn't really fit under 1 on 1 sports, since there's not opponent. Most have classified it as a martial art, as it's just as much a mental discipline as it is a physical one.
For more information, check out the following sites.
http://parkour.nethttp://americanparkour.nethttp://urbanfreeflow.comhttp://pawa.us