Making an emulator is legal, distributing ROMs for it is not. You see ROM sites get shut down all the time, but does that happen to emulator sites? No, b/c the emulator doesn't actually include any copyrighted content from Nintendo, so it's out of Nintendo's domain. Furthermore, homebrew NES games exist, so emulator's aren't
just for copyrighted ROMs
.
Making an emulator for the Zune is certainly a difficult problem. Just don't try to stop innovation in the name of copyright.
