This morning Xbox SmartGlass made its long-awaited debut on the Amazon Appstore. You can now download Microsoft's second-screen app for the Amazon Kindle Fire and Kindle Fire HD, fitting perfectly on the display of all Fire and Fire HD tablet models. With Xbox SmartGlass, which has been available for iOS, Windows, Windows Phone, and Android for the past six months, users can navigate and control their Xbox 360 consoles right from the tablet or smartphone.