Poster may be referring to the phone address book scandal, probably only one example. In that case importing your facebook contacts from your phone grabbed your entire address book, with what looked like account placeholders for anyone in your phone that wasn't already on facebook. Oh, and it published all their phone numbers too.
I'm sure facebook has myriad nefarious ways for tracking everyone you interact with regardless whether they have an account.
And do we need to point out Double click got caught tracking individual users and lying about it over 10 years ago.
Some sources would obviously be helpful, but I don't think anyone is kidding themselves about what's going on.
It was a blog post I can't find right now, but it's easy enough to reproduce: I deleted all the cookies from Facebook and then open a tab to a site with the Like button. A cookie for facebook.com is created called "datr" with an obvious ID and an expire date two years from now.
