There's a ton of resources out there for Silverlight, and for the most part all of this applies to Silverlight for Windows Phone. My limited experience so far has been quite postive. I took a simple game I wrote for Silverlight and cut and pasted the XAML and code into a new Windows Phone application and pressed F5. It ran without modification, the only thing I couldn't get working was the sound.
If your interested I just posted the source code on my blog.