While preparing for a talk with John Papa on Silverlight TV, Jesse Liberty created two applications - a traditional Silverlight (Web) application and a WP7 application using the same code. His purpose is to convince you that Silverlight programmers are instant WP7 programmers.
There is no doubt that as you dive deeper into WP7 you’ll run into differences between creating Silverlight applications for the web and for the phone, but these are (and will be) well documented and relatively rare. As an experienced Silverlight developer you are, really and not just hype, an experienced Windows Phone 7 developer. That means that rather than concentrating on syntax or on the API, you can focus on the design of your application.