iOS 8 will support "peer-to-peer AirPlay discovery and playback", which means that you won't need to be connected to a wireless network to use AirPlay. That's a really nice evolution of Apple's wireless media streaming protocol.
The tidbit was discovered buried within the enterprise section of Apple's iOS 8 preview. As written, the new peer-to-peer connection feature would allow iPhones and iPads to connect to Apple TVs even if they're not connected to the same wireless network. That's relatively simple use case, but it's got broader implications because it means that if two AirPlay devices can see each other they can directly connect.
In fairness, this functionality has long been available through the DLNA wireless protocol, and has been used by audio manufacturers like Pioneer to get around AirPlay's limitations. But it's always nice to see Apple open up its popular technologies to broader uses. [Apple via Apple Insider via The TechBlock]