The advertisers have a hole big enough to drive a truck through anyhow. They can simply ignore the setting, as many are doing now, and continue on their way. In fact, a WSJ article in this mornings links at »blogs.wsj.com/digits/2012/10/02/···k-pledge
says they already work around the setting.
Unless your a running utilities such as AdBlock and Ghostery, you are trusting the advertisers to honor your request which is like trusting Bernie Madhoff to take care of your bank account.--
I support the right to keep and arm bears.