Is it possible to install Xamarin Mono on Fedora (Linux)?
As CSharpRocks mentions, you can install the Mono runtime on most distros.
However, the Xamarin products are NOT Mono; instead, they are development tools and frameworks that run on top of Mono (I can't really say they're a super-set of Mono, as they don't support everything Mono does). Currently, the Xamarin products only support developing on Windows and OSX, and only target Android, iOS and Windows Phone devices.