This is from a story in today's NYT: http://www.nytimes.com/2012/06/05/science/big-datas-parallel-universe-brings-fears-and-a-thrill.html?nl=todaysheadlines&emc=edit_th_20120605 :
Mystery of Big Data’s Parallel Universe Brings Fear, and a Thrill
By DENNIS OVERBYE
Not long ago, a woman in Tacoma, Wash., received a suggestion from Facebook that she “friend” another woman. She didn’t know the other woman, but she followed through, innocently laying our cookie-crumb trails through cyberspace, only to get a surprise.
On the other woman’s profile page was a wedding picture — of her and the first woman’s husband, now exposed for all the cyberworld to see as a bigamist.
OK, now go back and read that again...though I know you already did read it a few times to see if it said exactly what you thought is said...which it, incredibly, did.
Here's my thought: I think the same kind of person who would friend someone just because Facebook recommended it is the same kind of person who would not figure out that their spouse was also married to someone else.