How can I opt out of Apple iAd data collection?

How can I opt out of Apple iAd data collection?

UPDATE: iOS 6 users who are not interested in targeted ads can now limit ad tracking. Navigate to Settings -> General -> About -> Advertising -> Limit Ad Tracking -> ON.

Apple intends to use consumer data from iTunes to target your iPhone with specific advertising within apps. The iAd program has already launched, but if you're not interested in Apple using your data to find relevant ads you can opt out.

Opting out will prevent Apple from collecting and analyzing data from your iTunes account in the iAds program. To opt out you must be running iOS 4 and visit this website on each device you are interested in opting out with:

If you receive the message, "Unsuccessful Opt Out," wait a few hours and visit the URL again. After you have successfully opted out your consumer data will no longer be used, however iAds will still appear on your device.

Apple uses several targeting options and metrics in iAd campaigns.