Using Monodevelop (Mono IDE) is the fastest way to write a desktop app on linux (vide recently announced Pinta). Really great stuff.
But what if you don't want to make a Mono app?
In the root post, j23tom claimed Monodevelop was the fastest way to develop desktop apps on Linux, but are they Linux apps or are they .NET apps that also run on top of Mono?
It seems that "(Linux|Windows|Mac|BeOS|whatever) app" doesn't have the same meaning today...