I'd never heard of it till now. It seems like a rather sound technique. By letting the roots systematically die (in a controlled fashion), they are forced to branch out. It seems like most anyone who has planted in loosely woven fabric containers may have been unknowingly accomplishing this. I've never seen a comparison between air pruned or "classic" planting, so I have no idea of the possible benefits. Thanks for sharing though, always good to learn something new!

Jay

Here is a link that might be useful: Air-Pruning

I don't know if this guy information is correct but check this out:
https://www.youtube.com/watch?v=ptgJn15TmRM