Yes, this is the thing that bugs me as well, about the whole concept of social media offered by companies that think information about friends/associations should be a commodity... There's no way to opt out as others provide information about you even if you don't participate.
Maybe we can get "Do Not Track" barcodes tattooed on our foreheads.
I'm half serious about this (OK, maybe not the tattoo part) -- some creative RMS or legal type needs to come up with some shrink-wrap-like default privacy opt-out agreement that subverts all this crap, in the same way that open source licenses turns copyright around.
Example: a single bar code that anyone can place on their shirt, clothes, whatever. The assumption being that any system capable of facial recognition is also capable of reading a barcode... And that the meaning of the barcode - reflected in an online "trackwrap" license - is essentially "this person can not be tracked," or more exactly, "any person/organization voluntarily tracking this person in also agreeing to the terms of the agreement posted online at www.don'ttrackmeblablabla.org"
Anyone want to take a crack at this? I'm willing to pitch in.