I have not tried these but i am thinking about it.
Vibrams don't fit my feet (or budget), so I opted for an invisible shoe kit (http://www.invisibleshoe.com/) for about $20. These look intriguing, though. I think I'll keep them on my radar.
Started PB late 2008, lost 50 lbs by late 2009. Have been plateaued, but that thing may just be biting the dust: more on that later.