Either you're building it yourself, and then you probably already have a compiler that supports C+11, or you're not, and you'll just have to wait for it to make its way to your favorite package manager / dependencies package.
Oh I'm not worried about the compiler's support. But since mingw-gcc is not supported by the yaml devs, there's no guarantee that their newer code keeps compiling on it.
Whenever a library proposes a pre-built package, I use it. Otherwise I have to compile it, and my current toolchain can compile 17 libraries this way (6 of them are required for compiling OpenXcom)
I'm very wary of upgrading, because each time I do, one of the older libraries stops compiling...
In case anybody needs it in the future, I attach here the yaml-cpp-0.5.1 which I use for OpenXcom.