Opt out of iAd location and data tracking cookies
You can opt out of Apple’s new iAd location and data tracking service, which will use gathered data on you to serve targeted ads through Apple’s new iAds platform.
To opt out of iAd cookies, visit http://oo.apple.com from the device you wish to opt out with.
Note that you must be running the latest iOS 4 or you will get an error, since iAds requires iOS 4 to run. You will need to view that website directly from your iPhone, iPod, or iPad, and access the site individually per device if you want to opt each out of the service.
Without the iAds location and data tracking cookies, you will just be served generic and less targeted ads.
Personally, I don’t mind location relevant ads as long as they don’t pass on personal data, and I have even found some location based ads to be helpful in the past, so I am not opting out of the iAds cookies at this point.