As a long time Windows developer who thrives in Visual Studio here's my 2 cents:

I want a Maemo GUI development environment that runs natively under Windows and can fully emulate a Maemo device with no desktop Linux involvement whatsoever.

Why? Laziness for one, as was noted above-- but also to pull in potentially thousands of developers who really don't care what OS is on a mobile device as long as they can develop for it using tools and environments with which they are familiar. This way we really facilitate inclusion... and may just win over a few OSS converts along the way.

I have been begging Nokia for such a solution for 2 years. I hope it's close...

FYI: Symbian has had this for years.