What are the main benefits of using Mono over Java?

What are the main benefits of using Mono over Java (or any other "free" or Linux-friendly language/runtime)?

Mono will always trail behind the latest developments in the .NET framework, why would you want to use Mono over another traditional open-source language/framework (Java)?

EDIT: Like someone mentioned below, I guess the root question is, why would you want to use .NET on the Linux platform?

Solution

The answer is pretty obvious: because you want to use .Net on Linux.

This of course begs the question (which I think is really what you're getting at): why would you want to use .Net on Linux (over Java)?

Lots of reasons:

Common code between your server and, say, a WPF or Winforms app;
Use of a particular .Net language, like F#;
Language features that aren't in Java (closures, operator overloading, partial classes, runtime generics, indexers, delegates, LINQ, var types, etc etc etc);
Your skills or those of your team are already in C#;
etc.