Check out http://www.chirunning.com/shop/home.php - he has a very good book, and, I've heard, an excellent DVD on the method. They also have a group of certified trainers spreading the word. ;-)

It is similar to "pose running" and forefoot running - check out the information at the Newton Shoe Company here - http://www.newtonrunning.com/run_better.php - and is essentially a controlled fall. You keep your body straight, lean from your ankles, and control your fall - the steeper the lean, the faster the pace. It really is effortless.

The nice thing is that you land on your fore foot, when done correctly, using the natural shock absorption structure of your arch, and severely lessen the pounding on the knee.