iOS 8 is now implementing MAC address randomization, where it randomizes your MAC address to networks while searching for networks.
One article describes it as:
One of those features, which is new in iOS 8, is the automatic randomization of MAC addresses when the device is searching for a Wi-Fi network. This makes it much more difficult to track a device by seeing which Wi-Fi networks have spotted its unique identifier.
However, once connected to a network, does it provide the true MAC address of the network card?