When the iPhone operating system was updated to iOS 4, (now iOS5) Apple added in a tool that would report to them on the quality of mobile signal and the quality of 3G coverage.
Taken from: http://radar.oreilly.com/2011/04/apple-location-tracking.html
However, that data file could also track and highlight everywhere you've been!
Since the article, Apple has fully opened up about the practice and allows the user to restrict the option.
Last modified: Thursday, 2 August 2012, 12:30 PM