If you work hard enough, you can do anything. Mono is slow, doesn't support everything, and most of the help you'll get is Windows specific.
I can't imagine using mono is for the faint hearted. For example in the new MS programming language thread [1] today someone mentioned they ended up giving up on the .Net GUI controls and using GTK# instead because it was so unreliable. Another mentioned that the transition from one SQL driver to another had left a lot of projects hanging in the wind with SQL breaking on mono but working on Windows.
Running C# the language with the BCL on mono is pretty painless, and offers a ton of functionality.