It wasn't touted onstage, but a new iOS 8 feature is set to cause havoc for location trackers, and score a major win for privacy. As spotted by Frederic Jacobs, the changes have to do with the MAC address used to identify devices within networks. When iOS 8 devices look for a connection, they randomize that address, effectively disguising any trace of the real device until it decides to connect to a network.

Any phone using iOS 8 will be invisible to the process

Why are iPhones checking out Wi-Fi networks in disguise? Because there's an entire industry devoted to tracking customers through that signal. As The New York Times reported last summer, shops from Nordstrom's to JC Penney have tried out the system. (London even tried out a system using public trash cans.) The system automatically logs any phone within Wi-Fi range, giving stores a complete record of who walked into the shop and when. But any phone using iOS 8 will be invisible to the process, potentially calling the whole system into question.

A privacy win for Apple

Combined with inventory and in-store video, the records are immensely valuable to stores as marketing data, and companies like Euclid Analytics and Path Intelligence have made an industry out of providing them. But now that Apple has embraced MAC spoofing, the practice of Wi-Fi sniffing may stop working entirely. With more than one in three US smartphones running iOS, and a notoriously fast adoption cycle for new operating systems, any data collected is likely to leave out a huge sector of the population.

The result is a privacy win for Apple users and a major blow against data marketing — and all it took was an automatic update.