Microsoft has released an update for the Windows Phone SDK adding two more emulators. This will enable developers to test how their 7.5 apps and tiles will work and look on an 7.8 system. The following is quoted from the Windows blog. Read full article here.

Today we are releasing the Windows Phone SDK Update for Windows Phone 7.8, an optional update that adds two new Windows Phone 7.8 emulator images to your existing SDK installation. These two emulator images should enable you to fully test how your Windows Phone 7.5 app’s Live Tiles will look and behave when they are run on a device running Windows Phone 7.8. New phones with Windows Phone 7.8 are beginning to ship, so it’s a great time to update your apps to take advantage of the new Live Tile experience and to reach the new markets that Windows Phone 7.8 makes available.