IIRC, Microsoft didn't publish that Vista is going to be completely based on .NET. Well, they did in the beginning and later said its not going to be. I am not surprised if Vista is not built on .NET.
But the 3 pillars WPF/WCF/WFS are (I think) completely .NET
I see .NET as a separate piece which can integrated later on. I am waiting for WinFS(holy grail)....
WCF is completely, WPF some parts are written in managed some are wrappers to native, about WinFS, core parts are written in native (C++), but API is written in C#. Why did they chose C++ instead of C#? because you can't use .NET at this level, what is .NET?
an abstractisation layer build on top of the OS...
And .NET is not only a piece of software (is a a great piece of software, but) is much more.
I agree with Russinovich, from a developer standpoint .NET is the future .NET is the present. And someday something like
this will make all of our dreams reality (writting OSs in C#, drivers, core elements etc.)