Apparently was being included as a side effect of another header include in Visual Studio 2011. To build on 2012, I needed to add the include explicitly to stdafx.h.
Steps to build in Visual Studio 2012:
Run "node-gyp configure"
Open "build\sqlserver.vcxproj" in visual studio 2012
Visual Studio will ask if you want to update. Agree, then save all changes.
Run "node-gyp build"
Build with Visual Studio 2012
Does this fix still build using Visual Studio 2010?
Yes. We include the STL headers together, so the order will not matter.
Great! I'll wait for @jkint to finish his RIs so that he can then pull this in. Thanks! :)