The Associated Press put out an article this week about the ongoing trend of employers doing something stupid: asking applicants for their Facebook passwords.
Why stupid? Let me count the ways:
1) It makes the applicants feel like they've applied to a totalitarian regime. And they'll tell others, which goes to your reputation. And what do we know about employer reputation? It drives who applies for your jobs.
2) Employers are likely to see things they wish they hadn't. I don't just mean people passed out drunk at a party, I mean things like religious affiliation.
3) If you're trying to access their profile on your own, many are marked private and you won't see anything.
4) If you ask them to log into their account during the interview, it's like asking to see their personal diary.
5) The content on people's FB page is largely outside their control (e.g., comments, photos they're tagged in).
Oh, and let's not forget:
6) The content of someone's profile--aside from things like education and work history which you should have already--is likely to be totally unrelated to job performance, regardless of its potential usefulness, because frankly most employers aren't graduate students in psychology who have received training on interpreting Big 5 characteristics.
The only caveat I can think of is when this request is made as part of a full background check, in which case pretty much your life is an open book.
Facebook, notoriously unpredictable regarding its privacy policies, subsequently warned employers not to do this...but I don't anticipate that this will stop. Why? Because employers are obsessed (rightfully so) with getting as much--and as varied--information as they possibly can.
This just isn't the right way to do it.