Security researchers Alasdair Allan and Pete Warden have uncovered a file that the iPhone and iPad 3G use to record your location history for as far back as the user has been running iOS 4. For iPhone 4 users, that means ever since they got the phone.
What's even more startling is that this location file is synced and stored by the iTunes computer and then carried through for as long as the user retains this backup. This means that it can be continually updated even if the user upgrades and changes his device.
Thus far Apple has not yet commented on why it introduced this location recording functionality in iOS 4. What Apple does mention in its 15,200-word iTunes user agreement is something to do with location-based services.
"Apple and our partners and licensees may collect, use, and share precise location data, including the real-time geographic location of your Apple computer or device. This location data is collected anonymously in a form that does not personally identify you and is used by Apple and our partners and licensees to provide and improve location-based products and services. For example, we may share geographic location with application providers when you opt in to their location services."
The authors have blogged about this matter at O'Reilly Radar and have even made an open source program that can use to read the file stored by the iPhone/iPad and iTunes and show exactly where you've been with your device in the last year.
Read more at the Guardian.