Most .NET developers are ASP.NET developers, developing for Microsoft's web server. ASP.NET is brilliant; I've been working with web development for ten years and it's really just a generation ahead of everything out there. But it's a server technology, so clients can use any kind of desktop they want. And it runs pretty well under Linux using Mono.
None of this bodes well for Microsoft and the profits it enjoyed thanks to its API power. The new API is HTML, and the new winners in the application development marketplace will be the people who can make HTML sing.