NuGetProvider is a OneGet (PackageManagement) provider. It primarily supports finding and installing packages from NuGet.org. It is also used by PowerShellGet for finding and installing PowerShell modules from PowerShellGallery.
It supports FullCLR and CoreCLR, meaning works for Windows, Linux, and OSX as part of PowerShellCore.
As a git submodule, it is compiled and tested with OneGet together.
For more information, see OneGet wiki.