There is a combo cover+light available for the 900. I am thinking about going to the Sony store to check it out in person. However, I've already ordered the Kandle light off Amazon (before I knew about the combo cover+light). It's should arrive tomorrow. The reviews for the Kandle are pretty good. Although the drawback is that its designed to match the Kindle.
http://www.sonystyle.com/webapp/wcs/...52921666067714
http://www.amazon.com/Kandle-WideLip...3851729&sr=8-1