The Xbox Companion Application for Windows Phone is now available on all Windows Phones. You can head over to the Windows Phone marketplace and download it for yourself. The decription states the following about the application:
Discover great entertainment with the power and convenience of your Windows Phone! Search for your favorite movies, TV shows, music, and games, and play them on your Xbox from your phone. Xbox 360 console and Xbox LIVE membership required.
So if you have an Xbox and you have an Xbox Live account, then it should be worth downloading your yourself. There are a lot of benifits to using this application and it demos some of the future features that could be integrated with Windows Phone and Xbox Live. This could even integrate with Windows 8 in the future as there will be a lot of Xbox features on Windows 8 in the future. If this sounds good to you, then you can download it here.