What is the best API to combine C++11 async/futures with Windows asynchronous IO?
The Tips and tricks for developing Metro style apps using C++ presentation covers this at 59:13. The raw interface uses callback objects. In practice, people are likely to use the simplified interface offered by PPL.
Windows 8 async will probably be done through PPL. You can read more about that here.
From my understanding, Windows 8 and PPL uses task-based scheduling and cooperative blocking. While std::async and std::future use thread based scheduling and preemptive blocking. Thus they are not compatible.