I own one--Ken Bob's--but haven't read it yet. I read Jason's free book/primer last year and found it quite helpful and well-written. Mostly, I like tuning into Steve Magness's Science of Running site. The elite runners have always run the same as barefoot runners, and have often incorporated barefoot running into their training regimens. Steve has a vast knowledge of the science, history, and training philosophies of this kind of running. Specifically barefoot running books seem most suited to guiding one through the transition, but some of their explanations/models are pretty idiosyncratic.