Google has added an opt-out to their Chrome browser so users can permanently avoid ad-tracking cookies. These cookies store information on users so ads can be more personalized (ever see an ad for an online store that you had been to only a few hours earlier? That's a cookie.)
The Federal Trade Commission has suggested a "Do Not Track" mechanism to protect user privacy and at least one other company, Mozilla (which creates Firefox) has also followed suit. However, the opt-out probably isn't optimum for Google which relies on third-party advertising for revenue. It probably explains the odd phrasing of its announcement on its Public Policy blog:
Keep in mind that once you install the Keep My Opt-Outs extension, your experience of online ads may change: You may see the same ads repeatedly on particular websites, or see ads that are less relevant to you.
U.S. & World
I don't think anyone cares if ads are less relevant to a user, but you can almost hear the pleading in the wording. It gets worse when you read more about the opt-outs, "Without a cookie, the ads you see on the web are likely to be less relevant and diverse. It also may result in less profitable ads for your favorite websites."
Whew! Talk about a guilt trip. As you can probably tell, Google is doing this to avoid government regulation. And while the Chrome browser plug-in will help, some advertisers don't participate in "self-regulatory efforts," according to Google.