Everyone saw that BBC advert with the French guy (David Belle) doing the gymnastic techniques on roof tops etc? Well its now getting a good following on the streets and there is now a UK parkour Association. [Only registered and activated users can see links. ]
My mate has started doing it and it does look like a good way to put a twist on general keep fit workouts. (of course you dont have to do it on roof tops!)
Check out the site cos some guys might be interested.