In the same vein, Hyland OnBase is moving to .NET as well.

What is the definition of success? Big apps written in .NET. They are out there. But if you're working deep in an enterprise environment, like many of us are, you're more likely working with product lines that began long before C# was around. So that environment isn't a good sample of the industry. I think it's undeniable that .NET is a "successful platform". The TIOBE survey has had it in the top 10 for quite a while now. And if MS' analysis is to be believed, half of the world's professional developers are working on .NET. Even if what they really mean is half of the world's Windows developers, that still smells like success to me.