Scot Hacker recently posted about urban freeflow, an impressive new exercise in fluid movement through urban landscapes. Participants run, jump, climb, drop, twist, rebound and flip on buildings, stairs, walls, hills etc. Urbanfreeflow.com is a great site explaining the behaviour and provides some great photos, very effective videos and tips on technique.
link update: parkcore.net, Urban-Climbing.com, tracers.ru, buildering.net, glossary
urban freeflow
Scot Hacker recently posted about urban freeflow, an impressive new exercise in fluid movement through urban landscapes. Participants run, jump, climb, drop, twist, rebound and flip on buildings, stairs, walls, hills etc. Urbanfreeflow.com is a great site explaining the behaviour and provides some great photos, very effective videos and tips on technique.
link update: parkcore.net, Urban-Climbing.com, tracers.ru, buildering.net, glossary

You might also want to take a look at www.parkour.org.uk - the site of the UK Parkour Association for a bit more insight.
By the way, it's worth noting that the sport is called le parkour, or in the media, 'free running'. 'Urban Freeflow' isn't the name of the activity - UF are a specific limited company operating a website about it.
The Parkour.org.uk site to me looks very much like something off of Blue Peter (rubbish and a bit sterile) whereas the urbanfreeflow one has a real street feel to it. Buildering.net looks good also.
The Urban Freflow website has a really simple and easy site to browse for everthing needed to start doing freeflow. I delved a bit deeper and found an insanely huge community of very helpful people.
The other sites listed are nowhere near as helpful.