The 'Do Not Track" feature Mozilla has been touting as a big privacy bonus in Firefox 4 hasn't exactly been attracting fans by the truckload.
The fatal flaw PCWorld pointed out in January still remains – DNT is just a place to put a request that advertisers not follow you.
That's like walking through lion country in the Serengeti with your pockets full of Lion Chow, carrying a sign saying 'Please Don't Eat Me.' (Which is foolishly Eurocentric; most African lions don't read in English.)
Neither do advertisers, at least not when the notes involve not eating browsers that look a lot like prey.
The first one, actually, is the AP News Registry, a usage-tracking service for content publishers, not a direct advertiser.
The second is an association of advertising associations called the Digital Advertising Alliance (DAA), which launched the Self-Regulatory Program for Online Behavioral Advertising in December, outlining goals and principles under which its members feel they can operate without getting regulators any more concerned about online privacy violations than they already are.
All the advertisers are insulated from too-obviously having to adhere to anything the Program endorses. If you join a club and promise to (mostly) follow its few rules, are you necessarily required to follow all rules of a club your club's leadership joins?
The third organization named in the release is actually the above-mentioned Program, which might qualify as a third club in the DAA membership-pyramid scheme.
So, at best, there are two "advertising" organizations supporting the Do Not Track feature in Firefox, one of which isn't an advertising company, the other of which has advertisers in its membership, but doesn't do any itself, and doesn't commit its members to anything.
Chrome has a similar DNT function; Internet Explorer 9 has one based on a protection list. None of them work, at least not yet.
Either advertisers don't support the function or they're too awkward for users because they're either all-on or all-off. You can't opt to be tracked by advertisers using the power for good (AP, presumably) and not tracked by those using it for evil.
It's good that Mozilla got someone to sign up to support DNT, if only nominally.
For the time being, if you want not to be tracked, use a different method.