Here is post from Clickz on December 21 in which the FTC tries to explain what it means by do-not-track.  Here is the key paragraph:

The recent FTC report envisions a do-not-track mechanism that lets consumers opt out of third party tracking for behavioral advertising, which is one of the most common forms of online tracking. If companies wish to share personal information with third parties for purposes other than online behavioral advertising, we think some greater form of user consent should be obtained. The system as currently envisioned would not apply to ordinary first party tracking or to a first party's use of a service provider for website analytics, assuming the service provider makes no additional use of the collected data.

It is important to keep in mind that the FTC is not proposing a blanket ban on all tracking.  Having said that, it is still not clear to me that the proposal is not based upon the perceived creepiness of tracking and the emotional response of many people to the idea that they are being tracked. 

The reason that third party tracking is “one of the most common forms of online tracking” is that there are substantial economic benefits to it.  No one has really answered the question:  What happens if do-not-track actually results in many people opting out?

One thing is likely, the people who make money as a result of this kind of tracking wont any more.  So, whatever “free” content is being supported this way will either disappear or will be paid for some other way.

Another thing that might happen was suggested to me by a well known entrepreneur and investor here in Boston.  A great deal of effort and ingenuity will be expended getting people to opt in.  If this happens, it could have a lot of ramifications.  One consequence that he suggested is that once people opt in, they will have expressly agreed to the use of their information and there is likely to be much more far reaching and free ranging use of their information compared to the current system in which abusers are likely to be outed unpleasantly one way or another.  A second consequence that he suggested is that businesses will try to position themselves as first party providers in various ways and thereby evade the ban.  Finally, he suggested that the cost getting people to opt in will simply be added to the cost of innovation.

One thing is for sure, there is significant money to be made through behavioral advertising.  Until the cost of getting to good quality behavioral advertising becomes so high that it become uneconomical to go there, the money will be seeking ways to get there.