Some objective-C code I've seen for the iPhone is UGLY as sin... and I would be flabergasted if Android decided to support that. Although I don't know anything about Android development.
But my point is... if you were to convert an iPhone app to Windows Phone...
The work will be in converting O-C to C#... not OGL ES to XNA
Android does not use Obj-C, it however has a C API.
You remember the language "C", the father of all C-like languages including C#? Perhaps you used it once or twice before?
Well Objective-C is a true superset of C. As in ALL C CODE IS ALSO OBJECTIVE-C CODE.
Yes. Objective-C is just how would you say, an "extention" to C. Not
an entirely new language.
OpenGL ES is a C API. Not an Objective-C API. That's okay, because "Objective-C is a true superset of C".
"Android does not use Obj-C, it however has a C API."
Do you get what I am saying?
You are converting C (iPhone) -> C (Android), OpenGL ES (iPhone) -> OpenGL ES (Android). Wow, you really aren't converting anything.
WinMob may very well be impossible to program with C, well then, this OpenGL ES thing is mostly a moot point.