Why are iPhones tracking users' whereabouts?

Apple Inc. (AAPL) appears to have a new security problem on its hands with iPhones running on iOS 4. A pair of security researchers have discovered a hidden file on the device that logs the users whereabouts and copies it to the owner’s computer whenever it’s synchronized with iTunes.
Pete Warden and Alasdair Allan have put up a website that details how the information is logged, but it appears there is little that users can do to opt out or avoid the previously unknown feature altogether.
According to Warden and Allan, the file contains the latitude and longitude of the iPhone’s recorded coordinates with a timestamp.
“By passively logging your location without your permission, Apple have made it possible for anyone from a jealous spouse to a private investigator to get a detailed picture of your movements,” Warden wrote on the site.
The pair haven’t found any evidence of the data being transmitted beyond any iPhones and the computers it synchronizes with, but notes that any user with access to your PC can read the data in its already easily-readable format.