Crank out Visual Studio 2012!!!!
As you begin coding a beautiful, immersive Windows 8 app, you will think about some key considerations highlighted in this video, including ensuring that your app runs harmoniously on multiple form factors and devices and works seamlessly with touch, pen, mouse, and keyboard. You will also want your app to be safe to install and use, and take advantage of a new runtime and programming model.
Windows Phone to Windows 8: Differences between Silverlight and Windows Store apps using XAML
TIP: Windows Phone and Windows 8 share a common UI, yet there are a number of differences between the UI capabilities of the two platforms. Learn more about how the key differences can influence your app.
Windows Phone to Windows 8: Mapping Windows Phone 7 APIs to Windows Runtime APIs When migrating your app, your API is key. Read more about mapping of Windows Phone 7-specific APIs to their WindowsRT counterparts.
You will always have this list of Windows 8 resources at your disposal: