Typically, you develop an application for Windows Phone 7 by using Microsoft Silverlight and one of the managed programming languages—usually C# or XNA.
A Windows Store app using C++, C#, or Visual Basic, using XAML, is the preferred model for ports from Windows Phone 7. If you are familiar with Silverlight, you can port to a Windows Store app using XAML by using familiar languages like C# or Visual Basic, and a similar set of UI elements and APIs.
For more detail about porting a Windows Phone 7 application to XAML, read Migrating a Windows Phone 7 app to XAML.
However if your a game developer then you can move your existing Windows Phone XNA using Monogame.
Porting to Windows Store app using MonoGame
For some background you can read these posts:
During the ThreeThing Game event, Dean Ellis @InfSpaceStudios talked through the porting of a one of the teams Windows Phone game, Shear Carnage to Windows 8, the initial port took 7mins 47seconds, which is pretty impressive stuff!
Some of the key features, the team now need to work on now to get the app store ready is..
Overall this is pretty stunning for existing Windows Phone developers taking existing or new phone apps to both the Windows Phone Marketplace and Windows 8 Store.
Good one Lee
Could have added some code snippets.
Srigopal if you want code samples see the three step guides above.. source code and examples included.
So the subtle suggestion here is that XNA is dead and we should abandon using XNA for something else in order make it to the windows store???
We have already stated that XNA is no longer supported for Developing Windows 8 Store or Windows Phone 8 apps see msdn.microsoft.com/.../jj207003(v=vs.105).aspx
However we are supporting the development of XNA Apps for Windows Phone 7.x see msdn.microsoft.com/.../ff472340(v=vs.105).aspx
However you can use Monogame to wrap exisiting XNA assets for use in Windows 8 apps see the tutorial 3 step guide above there lots of Windows 8 games in the Windows App Store which have used Monogame including ARMED.
Why support Microsoft doing stupid things? Microsoft abandoned XNA for Windows 8 and don't give a solution for XNA Developers. This is very bad practice!
Monogames aim was to port XNA to other Platforms than Windows.
I suggest all people to port XNA -> Monogame and than go with Linux or MacOSX until Mircosoft adds XNA support to Visual Studio 2012 and Windows 8.