I found it fascinating, too... it send me on a hunt to try and better understand their World3 model. I bought Wolfram SystemModeler since one of their extensions has the model, and I also found some online resources that have modeled it through javascript too. One thing that was a little disheartening is that I found that one of the inputs to the model appeared to be highly determinant, and the initial values chosen seemed controversial. If I changed the initial value to something else that still seemed within a reasonable range, the model projections didn't seem so bad.

I wish I could remember details, I've been searching my hard drive for my notes.