Where have you been? Your iPhone knows.
Twitter has been ablaze recently with revelations that iPhones and iPad 3Gs are secretly recording your every move, and have been doing so for about a year now.
According to Alasdair Allan and Pete Warden, the duo who made the discovery, the information is stored in a file that is backed up to your computer and survives handset upgrades:
What makes this issue worse is that the file is unencrypted and unprotected, and it's on any machine you've synched with your iOS device. It can also be easily accessed on the device itself if it falls into the wrong hands. Anybody with access to this file knows where you've been over the last year, since iOS 4 was released.
The duo also have an open source Mac app call iPhone Tracker that you can use to visualize your own location data. The screenshot at the top of this post is a portion of mine from this past year, limited to the area around the UK (the actual data ranges to the US and various Scandinavian countries).
According to Alasdair and Pete, there is no reason to believe that the data is being communicated to Apple. Still, though, the fact that Apple did not disclose that it was recording this information doesn't sit right with me even if it feels more like an oversight than a malicious act. I hope they will issue a statement on the matter to clear things up.
All that said, a lot of us do disclose our locations via services like Foursquare, Gowalla, and – for the masses – Facebook checkins. The difference, of course, is that you are aware of the fact and engage in it willingly.