JC Cimetiere explains how you can leverage your iPhone development expertise to build Windows Phone 7 applications.
Source: The Windows Phone Developer Blog
If you are a .NET developer, learning Windows Phone development is not really “change.” Instead, it is more of a continuum, where you just add new features to what you already know. If you are an iPhone developer, new to Windows Phone (and .NET), yes this is different. But don’t worry. The learning curve is not as steep as you would imagine.