If you want weighted exercises, check out
www.crossfit.com . That is what I would be using if I WERE to use weighted exercises. Otherwise, I'm operating on two assumptions:
1.) most of the people I train with regularly don't have access to gym equipment
2.) many others don't have enough time to make it to the gym every day
if you combine this with the fact that a properly designed bodyweight program can garner most of the same beneifts of a weight program, you begin to see why it will be all bodyweight skills. I've also found that the less excuses you have for skipping the workout, the better, and if we're operating with minimum equipment, that eliminates many, if not all of the excuses I commonly hear

I will be attending the Crossfit certification seminar in February, though, so I believe wholeheartedly in their method. If you ever have any questions about how to incorporate weightlifiting into a practical and functional workout for Parkour, don't hesitate to shoot me a line.