It is possible to access Windows Marketplace using code within a Windows Phone 7 application. This is a useful way to offer users of your application other applications that you publish, or to help them find upgrades and new versions of the application.
The Windows Phone 7 operating system includes an API that allows your application to open the Windows Marketplace hub on the phone to show specific types of content, such as applications, music, or podcasts. You can also open the hub showing a filtered list of items from one of these categories using a search string, or it can show just a specific item if you specify its GUID content identifier. Finally, you can open the Reviews screen. You can also include a direct link to a specific product on Windows Marketplace in non-Windows Phone 7 applications (such as websites and desktop applications).