Yes, admittedly I have never even seen C11 code in the wild.
I still dont think MSVC fully supports C99 either which is quite annoying. Microsoft's excuse was that they would rather spend time on C++0x functionality.
Now, as a C++ developer, I agree with this choice. Unfortunately their C++ support is a bit lacking too :/
With Microsoft's new direction with C++ (Albeit C++/CX) perhaps we will see them make up a bit of ground here in the near future including in C support.