MVC5 still not working tho. Good thing we have Nancy. Edit: Seems like many do not know about Nancy, check it out, some even say it's better than MVC. The good side is that it's 100% compatible with Mono because they run tests against it too so you can host your C# websites on Linux. Github: https://github.com/NancyFx/Nancy
What *nix needs is an OWIN compatible web server.
I'd say there are plenty of alternatives to OWIN (and the .Net stack) for *nix. That's probably why there's not much interest around Mono, too.