I have run over 30 hours barefoot and 23 hours in Vibram FF this year, mostly since the summer. Go to
http://runningbarefoot.org/ for a good resource on running barefoot. I believe you can get injured if you try to use VFF before learning to run barefoot. For the past 3 months I have run pretty much every run either barefoot or with VFF, now I struggle to get comfortable in my old cushioned running shoes, and even run in my VFF on the road. The changes necessary for foot strike and tendon muscle changes and strengthening take a fair amount of time to used to and I am still running generally slower on my runs than I did with shoes, but I am injury free and like the changes that have taken place in my running form.
Running barefoot gives you the sensitivity in your feet to get a better feedback and will help keep you from doing too much too soon. I have also run barefoot for the past two years as a supplement to my running, so take it slowly, or you can get injured