Getting Started with Silverlight Applications for Windows Phone 7
I’ve gotten the Windows Phone App fever. The past few days I’ve been creating my first Silverlight applications for Windows Phone and I have to say I’m impressed with the development environment and the emulator. I’ve done a lot a work with Windows CE and Windows Mobile in the past, so I've seen my fair share of device emulators, and the Windows Phone emulator is very nice and easy to use. Quick tip, once you start debugging, it does take about a minute to load the emulator, but you do not have to shut it down between debug sessions. Simply choose “Stop Debugging” in Visual Studio and the emulator will stay loaded. Next time you F5 into the debugger, the app loads right up in the emulator.
If you haven’t developed Windows Phone applications yet, here are some resources for getting started.
Here’s the main Windows Phone Developer portal. There are links here to download the required tools as well as a ton of resources for developing apps. The tools include a version of Visual Studio 2010 Express for Windows Phone which has a Windows Phone emulator.
The Windows Phone App Quickstart is a good place to get started with your first Silverlight application.
The MSDN Silverlight Mobile Platform Development section has some great information. And the core Silverlight MSDN reference API docs are here. (Note, in the member tables there will be an icon of a phone 
if the member is supported on the Windows Phone.)
And the Expression Blend and Design team blog has information on using Blend to develop Silverlight applications for Windows Phone. (Note, from Jamie Rodriguez blog: "Important Note: If you are developing in Silverlight for Windows Phone 7, do not install the released version of Expression Studio 4. You must continue to use the Blend 4 Beta and Add-in Preview for Windows Phone. This Beta will be refreshed with each Phone SDK pre-release and will be unified with released Blend 4 in a service pack which will release when the Windows Phone SDK releases.")
Expect more posts in the coming weeks on Windows Phone application development.
Enjoy,
--Brian