Do Not Track has been effectively dead for 1.5 years. Very few advertising companies ever supported it due to Microsoft's decision to buck the spec and enable it by default for all IE10 users (a transparent attack on Google by a company whose own advertising business had just imploded in a $4B write-off).

The original agreement was carefully hashed out between advertisers and browser vendors with the understanding that only a small percentage of users would be opting out. When Microsoft reneged on that, the advertising industry backed out.

Whatever you think about online tracking, the voluntary nature of DNT and the complete lack of enforceability (there's no way, as a user, to determine whether a company is following DNT) made it pretty useless. True privacy protection needs to be on the client side (like script blocking or 3rd party cookie blocking), not on the server side.