Interesting technology. Wi-Fi Direct allows devices to talk to each other in a manner similar to Bluetooth (Engadget has details). I see a lot of overlap with Zeroconf (Apple’s Bonjour, Microsoft’s Universal Plug & Play): You need to see what services are available in your environment and you need to be able to connect to them. For Zeroconf, the environment is the LAN you are currently in. For Wi-Fi Direct, the environment includes any supported device within close range. I wonder how much Wi-Fi Direct is compatible with other protocols. It would be a shame to have yet another protocol for service discovery.
Wi-Fi Direct probably supports pairing and that is also useful for Zeroconf. For example, by locking your printer away, you can prevent people on your LAN to print on it.