Tara Parker-Pope in an article on the NY Times titled Running in Vibram FiveFingers:
The American Council on Exercise, a nonprofit group that reports on fitness, recently sponsored a small study to learn more about the popular footwear. Researchers from the University of Wisconsin, La Crosse, asked 16 women, all healthy recreational joggers ages 19 to 25, to spend two weeks getting used to running in the Vibram FiveFingers, a snug, glovelike shoe that weighs less than five ounces. The women were advised to use the shoes, the best-selling brand of barefoot sports shoes, three times a week for up to 20 minutes a day.
It suggests running barefoot does put less strain on your body because there’s less impact on landing. However, only if you adjust your form and land on the ball of the head instead as on the heel as with normal running shoes.