If you interested in developing with Silverlight on Windows Phone 7, you may want to read this post of Jeff Brand in which he explains how to add nice transitions between different pages of your application.
By default, Windows Phone page transitions really aren’t transitions at all. The new PhoneNavigationPage is just popped into the root PhoneNavigationFrame. Effective, yes. Cool, certainly not. Face it, modern mobile applications need to not only be functional, but also stylish. Simple “snap” transitions just don’t cut it.