What *nix needs is an OWIN compatible web server.
NoWin, Nancy, SignalR & Lego on the raspberry pi:
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.
SO close...
Edit: An open source program must never depend on binaries in the build process where those binaries can't themselves be rebuilt from source. Again, I'm not a zealot but as a developer I see dependencies on arbitrary binaries as damage and try to work around them.