This is scary.
Got an iPhone or 3G iPad? Apple is recording your moves
A hidden file in iOS 4 is regularly recording the position of devices.
Today at Where 2.0 Pete Warden and I will announce the discovery that your iPhone, and your 3G iPad, is regularly recording the position of your device into a hidden file. Ever since iOS 4 arrived, your device has been storing a long list of locations and time stamps. We’re not sure why Apple is gathering this data, but it’s clearly intentional, as the database is being restored across backups, and even device migrations.
Try it for yourself. I just downloaded the app (Mac OSX only) and relived my last year of traveling!