US Representatives Ed Markey (D-MA) and Joe Barton (R-TX) got their feathers ruffled when Apple changed its privacy policy in June to include language about location data. While this new change only described how CoreLocation has always worked, the Congressmen had some questions about Apple's use of the data. Apple has now responded, making it clear that none of the data—even that used for location-aware iAds—is linked to a specific user or device, and that no data is shared without specific consent from the user.

According to the response by Apple lead counsel Bruce Sewell, Apple does collect anonymous location data from iPhones in an effort to improve its own database of cell tower and WiFi hotspot locations. Devices running iOS versions older than 3.2 still rely on the databases from Google and Skyhook for these locations; these two companies are the "partners" with whom Apple shares data to determine the location of iPhones, iPod touches, iPads, Macs running Snow Leopard (which has a systemwide CoreLocation API), and Windows machines running Safari 5 (which uses the HTML5 location APIs).

Since iOS 3.2, however, Apple has used its own database of known cell tower and WiFi hotspot locations to assist in determining a particular device's location, especially for devices that lack separate GPS hardware.

Apple says that when location services are activated on a device and an app requests location data, Apple will anonymously collect data which includes GPS coordinates, any cell towers or WiFi hotspots that the device can see, and what kind of signal strength the device is reporting. It can also collect information about locations for when calls are made, and other situations which Apple uses to "improve service." The company says it only does this with user consent, and you give that consent when iTunes asks if you want to send anonymous data to Apple for diagnostic purposes.

Even when Apple uses location data for iAds, the specific location is turned into a zip code—Apple doesn't retain location data in that instance. When more specific location data is requested for certain iAds, the user gets the same "This application is requesting your location: OK or Don't Allow" warning that all applications give before using your location. Apple says it does not collect or share any personally identifiable location information that can be tied to a specific person or device for iAds.

Sewell noted in the letter that users can opt out of location- and interest-based iAds. Also, all of Apple's software includes an option to turn of the use of location data, including Safari 5, Snow Leopard, and iOS. iOS 4 goes one step further, giving users the option to turn off location services on an app-by-app basis.