The Apple iPhone has been found to be saving details of the handset's location at all times, complete with latitude and longitude co-ordinates and timestamps.
As if that wasn't Big Brother enough, this secret file is copied to the users' computer every time the device is synced.
It seems that the data storage began after the iOS 4 software update, since when Apple has been logging where you've been and when.
The news has sparked privacy concerns because the data, once transferred to a computer, is fairly easy to access by anyone who gets their hands on the machine.
The two developers, Alasdair Allan andPete Warden, who discovered the secret iPhone tracking have started a site to visualise the data found on users' handsets.
They note that the other major issue is that Apple is "passively logging your location without your permission" and aren't even protecting the data once it is stored.
"At first we weren't sure how much data was there, but after we dug further and visualised the extracted data, it became clear that there was a scary amount of detail on our movements," they wrote on the site.
"It also because obvious that at least some other people knew about it but it wasn't being publicised."
Apple is yet to respond to the location data revelation.