<p>I'm wondering if mono.net is included in the default installation of Ubuntu, Kubuntu, and Fedora, and other popular distros?</p>

<p>If so, does anyone have a good reason why NOT to use it to develop a new GUI application targeted mainly for linux?</p>

I'm wondering if mono.net is included in the default installation of Ubuntu, Kubuntu, and Fedora, and other popular distros?
I don't believe Ubuntu comes with it by default, Kubuntu certainly doesn't.
Ubuntu Intrepid, and probably Hardy, comes with Mono by default. Don't know about its status on other distros.
If so, does anyone have a good reason why NOT to use it to develop a new GUI application targeted mainly for linux?
If it's targeted mainly at Linux, why not use a technology that integrates better with the Linux desktop? Python and Java are good choices. Only use .NET if there's a large amount of legacy code you'll be re-using.