A reader sent me a link to this recently, http://wiki.csharp-online.net.
On first blush, I see sparse content, a slick MediaWiki implementation, and Google Ads... Wait! Is a Microsoft employee actually blogging about this?
[Please wait while I change into my Microsoft SuperSuit.]
I would be much more likely to use and support a C# wiki that runs on a Wiki that is actually written in C#, like FlexWiki.
Eat the C# dogfood!
FlexWiki is a C# .NET shared source project that you can contribute to, modify, download, and deploy on your own site. It's also a grassroots effort that Microsoft supports...http://spaces.msn.com/davidorn/. :-)
FlexWiki WikiTopics can now be stored in either a flat file database or in SQL Server!