Yesterday I picked up a pair of Vibram FiveFingers KSOs and am already in love with them. They are basically socks with soles and separated toes. The theory behind barefooting is that traditional shoes put your feet on a flat platform and muscles that would otherwise be involved in walking atrophy. If you wear shoes with a lot of arch support, you're enabling the muscles that support your arch to continue to be weak; going barefoot forces the muscles to get stronger. Shoes are undoing 4 million years of evolution. Or consider walking on uneven terrain in traditional running shoes—your ankle twists and bends to absorb the differences, as opposed to your toes and feet wrapping into the differences.
I went for a short (very short, 400m at most) run yesterday in my KSOs and felt muscles on the underside of my toes engaged. I went for about a mile walk today and felt the whole underside of my foot start to fatigue from my feet actually gripping the ground. I'm sold on the theory of barefooting, and (as my physical therapist cautioned me) will very very slowly ease back into it. I haven't run barefoot since I was like 4 years old.
Here's a lengthy article in New York Magazine on barefooting. I actually also ordered a pair of VivoBarefoot shoes (think slippers with 3mm kevlar soles that are designed to look like socially acceptable shoes) from Amazon, but the only pair they had in stock of the model I wanted turned out to be one size too small...NB, try on shoes before you buy them.