With less than 24 hours to go until Microsoft takes the covers off Windows Phone 8 once and for all, the company has released a companion app in the Windows Store that'll work in tandem with the new devices. The Windows Phone app works on both Windows 8 and RT devices like the recently-released Surface and replaces much of the functionality found in the Zune desktop client; it'll let you copy music, photos, and other media to and from each device, among other features.
Details of the Windows Phone companion app were leaked to The Verge nearly two months ago. At that time, we heard that the app would automatically install to your computer upon connecting a Windows Phone 8 device, but we're unable to check this without having one of the new phones in hand. However, we can confirm that it doesn't work with handsets running Windows Phone 7. You won't be able to do very much with the app right now, then, but you can check it out anyway by downloading from the Windows Store.