[jnky]

I don't know how precise the ad targeting exactly, but what if you narrow the base group down to your 19 fake accounts and your target user.

If you could the further filter your ad based on gender (as mentioned above), personal interests or other private data, you may be able to use your ad impressions to figure out things about an unsuspecting person.

I'd consider that a huge breach of my privacy.

[CRConrad]

But anyone who has your e-mail address -- a semi-public identifier, like your name or Facebook page -- can send you an e-mail. Is that also a "huge breach of [your] privacy"?

Is addressing you by name when one bumps into you on the street -- "Hey, Junky, did you hear about..." -- also a "huge breach of [your] privacy"?

That was the GP's question: How is this (targeted FB ad) any more a "huge breach of [your] privacy" than sending you an e-mail? (Or, my addition, than talking to you in the street?)

A weird and hugely convoluted way of talking to you, yes -- compared to, say, just posting a comment on your FB "wall" (do they still call it that?) -- but still: Just a way of talking to you, like e-mail or a Facebook wall posting.