That's a big topic of discussion in the running community these days. The current thought (fad?) is to strengthen the feet by eliminating support so one's own musculoskeletal structures do the job. There's no conclusive evidence for or against at this point, but it's what's going on.
Ya and to a certain extent it makes sense to me, but Im assuming they mean much lighter workouts if your barefoot? Ever seen Dual Survival on discovery channel? The dude Cody who is from AZ says he hasn't worn shoes in like 18 years?? And they go to some gnarly ass places on that show and he still isn't wearing shoes
When Ive tried to work out barefoot before I felt like I was going to injure myself a lot easier.