The last startup where I was CTO was largely based on the Microsoft .NET stack and we loved almost every ounce of it as a technology. Until, of course, we tried to hire startup and open-source minded engineers in the Microsoft-hate land of Silicon Valley. That's practically impossible.
StackOverflow and (hopefully) now Github will ideally do a lot of good in the next few years to break the stigma against C#.
It seems like the C# community at large contains Enterprise-oriented folks, who only like to consume open source and not give back. They just want to get their projects done and make a profit. I wish we could see more altruistic entities and startups embrace the technology. @haacked - fix it! Github seems like an ideal platform for change in this regard.
Oh, yeah, that startup was acquired and they threw away all our back end tech for no other reason than it was Microsoft based. It's not all bad, though, I do love my shiny Macbook Pro. ;)
Feature requests: - CodePlex migration tool (I have a project there...) - Github client for Windows - Github VS integration