Technically, Windows is no longer a windows technology, since Wine exists, but still it's mostly windows. Can you even run Visual Studio on another platform?
Visual Studio is still pretty dependent on Win32 / x86 under the hood - a lot of the UI was ported to WPF and more of the tooling, including the compiler, is being ported to C#.
So no, I think VS for Mac / Linux is still a ways off. They're moving in that direction though - wouldn't be surprised if they bought Xamarin in order to make it happen.
