Apple To Randomize Device MAC Addresses In iOS8 For Better Network Security And Privacy
Essentially, iOS 8 will generate a random MAC address while scanning for a Wi-Fi network, which means that companies collecting that data won't be able to align things as they have before to track your hops around the Internet. In iOS 7, Apple bars app developers from using MAC addresses to track the quantity of people that have installed their apps, but iOS 8 takes it a step further. As Apple puts it: "The MAC address used for Wi-Fi scans may not always be the device’s real (universal) address."
It sounds minor in the grand scheme of things, but it's a pretty meaningful step for privacy, and we're hoping that other mobile OS providers follow suit.