From Rosetta Code

Mono isn't just a C# implementation, it's also a .Net Framework implementation, and a few other things. (The Wikipedia page has quite a bit of info.) Not too sure what to do about that, except maybe give it a brief write-up and link to .Net & C#... or something. Does anyone have a better idea? -- Eriksiers 15:55, 28 October 2009 (UTC)

Apparently (from what I've been told) it doesn't have nearly enough of the libraries to run many C# apps that are out there in the wild, so while it is a C# implementation, it's not a full .Net impl. I have not had the time to independently confirm or deny this though. —Donal Fellows 16:42, 28 October 2009 (UTC)