From a developers perspective, developing metro style applications in Windows 8 is all about app contracts.
One of the contracts is the sharing contract, this allows apps to share data without knowing up front to which apps it will connect. This contract also allows sharing by using NFC (near field communication), without the developer knowing anything about NFC.
The cool thing about this is that, Windows 8 will start sharing data between 2 devices, when they are in reach of the NFC radio and you give permission by tabbing the two devices together.
What’s even cooler is the fact that after the initial “handshake”, the communication channel can be automatically upgraded to use Bluetooth, Wi-Fi or Wi-Fi direct.
So imaging, if you put two brand new Windows 8 ivy bridge tablet with NFC together, they can share music, video or picture files directly by using it’s 802.11AC 1 wireless adapters. Wireless sharing this data at 1gbit\s.
See the following screencast for more information:
Connecting and sharing with near field communication