Am I the only one a little creeped out by Facebook’s silent addition of a “People you may know” box which popped up on my profile?
What’s next? “People you may want to date?” It would go nicely alongside those ghastly, ubiquitous singles ads. Do you remember when Facebook didn’t have ads? I do 
(I’d be willing to be that if I changed my status to “In a relationship” they’d go away) How about “People you didn’t know smoked pot” or “People who you thought liked you but who make fun of you behind your back?” (Really, these aren’t so crazy – a few well thought out search terms or a Baysian algorithm could probably make more headway than we’d like to think)
It’s true that all the information Facebook uses for this feature is visible to you anyway, and Facebook isn’t doing anything that people don’t do on their own (trawl their friends’ friends lists for common acquaintances), but it’s still creepy.
Facebook didn’t ask me if it was okay to do this on my behalf. They didn’t announce that they were going to do it. They didn’t suggest that I add the feature. They just did it, silently. The same way they introduced Beacon.
Once it becomes okay for Facebook to do things on my behalf because it thinks I might like them (like searching for pot-smokers among my friends) it means I’m trusting Facebook’s judgement over my own.
The real reason this creeps me out is because it’s a reminder of exactly how much information is on Facebook. Most of it is lost in obscurity if I am manually eyeballing things, but the instant intelligent search is introduced to the picture, obscurity no longer provides any protection.