Yoshi (Tsuyoshi Yoshino), a member of the Triathlon Club of San Diego recently completed a masters degree on barefoot running. He used several club members as guinea pigs during the research.
Here is an article about him and his research that appeared in the New York Times.
http://www.triclubsandiego.org/stories/5059551.html
I lived in South Africa for a while (think Zola Budd) where many exceptional runners go without shoes and was impressed with the idea that it is far more natural. I spoke with a few who believed that running shoes remove the ability of the natural arch spring to do its job, causing more pounding to be transferred to the body.
That said, I wear the flattest shoes I can find as I am lacking the think coating of skin require to protect the bottom of the foot.