Well, of course I want to opt out of placement of cookies by advertisers. That sounds great! So I visited the Network Advertising Initiative site linked to try to do just that. And—sigh—of course there's a catch. It turns out that in order to opt out of placement of Facebook advertising cookies by more than two of the sites listed, I have to enable placement of cookies by third parties in Firefox across the board.
Um, no. I'm guessing there are many reasons why they chose to set up an opt-out system this way—and I don't purport to know any of them for sure. But this strikes me as a rather clumsy solution.
The best part? When I went back to the Facebook Site Governance note to comment on the issue, I found that despite the note supposedly being open for comment until November 5, I could read others' comments, but not leave any of my own. Awesome.
P.S. Facebook, "opt-out" is not a verb. "Opt out" would be the correct spelling; the hyphenated form finds more proper use as either an adjective or adverb.