Running without shoes can have a dramatic effect on gait.
A new study examined 713 subjects and videotaped them carefully as they ran with shoes and without shoes. The researchers found that without shoes, there was a decreased the prevalence of rearfoot striking.
Conclusions
This study provides evidence that running barefoot does have a dramatic impact on gait. Unfortunately, there is no way from this study to know whether this effect is favorable or unfavorable. I have heard multiple viewpoints on whether forefoot striking is actually better or worse for the body, and it is hard to say whether the effects of barefoot running would actually be desirable.
References