Digital rights advocates say that while the latest Apple discovery is worrisome, it's just one more example of the vulnerabilities related to location data.
"These location records can reveal a wealth of sensitive information about you: your attendance at a gun rally or prayer meeting, your frequent visits to a health clinic and more," said Chris Conley, a technology and civil liberties fellow at the ACLU of Northern California. "Control over this information needs to be in your hands, not Apple's."
If any good comes of this discovery, he said, it's that Apple is forced to answer some tough questions.
"I think people will be horrified to learn some of the places where their data is going," said Peter Eckersley, a senior staff technologist at the Electronic Frontier Foundation.
It's not just Apple that knows people's locations, but map providers like Google, cell phone companies and location-based services like Foursquare, he said.
"Location data is very sensitive," he said. It can reveal where you live and work, where you frequent for movies and dinner and even if you've spent the night at someone else's house.
Previously, Eckersley said, the EFF was concerned about location data stored with third-parties (like cell phone companies and location-based services), but this latest finding opens up another set of potential problems.
Once people realize how many parties can access their location data, he said, we will need to redesign our phones so that we can benefit from location-based services "without phoning home to 10 different mother ships showing where we are."
"The phone is such an intimate window into our lives," he said. "It needs to be treated with an appropriate level of caution."