C++/WinRT is now available on GitHub. This is the future of the Modern C++ project and the first public preview coming officially from Microsoft.
https://github.com/microsoft/cppwinrt
C++/WinRT is a standard C++ language projection for the Windows Runtime implemented solely in header files. It allows you to both author and consume Windows Runtime APIs using any standards-compliant C++ compiler. C++/WinRT is designed to provide C++ developers with first-class access to the modern Windows API.
Please give us your feedback as we work on the next set of features.