One of the concerns that web users have is that on line behavior tracking is getting out of hand. Web based entities know more about more things than what some people feel comfortable with. People want to be able to manage their privacy and there is now an effort (similar to the do not call list) by the FTC to be able to opt-out of web based tracking.
I believe that there is a need to place “do not track” approaches, but it will not be something that is quite as much of a blanket approach as the “do not call list”. Instead it will have to be something people will turn on and off as they need it. Many websites will not be able to function properly if tracking is not enabled, since these capabilities are the foundation for their existence.
I am not sure how the market will respond, but it will likely either be through subscription based sites that would allow you to be tracked through your explicitly logging in or through the user turning on and off the blocking technologies that will need to be embedded in the browsers. It should be something interesting to watch over the coming months.
There is also a post about Do Not Track by Nicholas Carr on his blog.