There's a good physician-penned piece on Well on doctors' use of Facebook. I think this clinician's personal policy is a very smart one:
I worry that it is impossible to maintain a perfect firewall, so I’ve decided to limit my online presence to the professional side of my life, keeping personal information off the Web. And before I post anything anywhere, I try to imagine what a patient of mine might think if she stumbled across it. Would it make her cringe? Would she feel awkward during her next office visit? Would this somehow compromise our relationship?
This means letting go of the fun and casual side of social media, but I think that’s simply part of the territory of being a doctor. It’s the same reason I don’t wear flip-flops and shorts to work, much as I’d surely love to. Giving up posting vacation pictures doesn’t seem like a particularly high price.
Previously: Social media brings up questions, ethical unknowns for doctors, Should you follow your psychiatrist on Twitter? and Physician 2.0: Do doctors risk becoming irrelevant if they ignore social media?