Android has Dalvik machine that's basically a JVM (but don't call it JVM due to patents and current legal disputes). Dalvik is a "clean room" implementation of a Java Virtual Machine (no copyright infringement yet) maded by Dan Bornstein (a Google Engineer), heavily optimized for Snapdragon and arm architectures. Even the linux kernel is patched to deeply integrate their environment (time scheduler mainly but even other subsystems) so it's not a "clean linux kernel".
No .NET ports for it and I don't even think they'd like to port mono to it.
Android apps are totally different to a common win32/64 .net app, even the workflow is different, every form (let's call it "activity") is an object and may be invoked by every app inside the "machine", there's no "main form" or a real starting point for your app.
.NET development really differs from the Droid that is more close to iOS (iPad, iPhone, ..) and even Palm (anyone using it yet ?)

Ben