The Wow product listing now states "Windows Vista / 98 / 2000 / Me / XP / 95, Mac OS X Intel, Linux, Mac OS X, Mac OS 9 and below."
Is Blizzard readying their 2013 Linux game play or is this a mistake out of Amazon? You'll need to wait and see shortly. It's long been known that Blizzard does maintain an internal Linux build of World of Warcraft over the years and I've personally seen it, thanks to my surfing buddy sources at the game company. Let's hope for any official announcement sooner rather than later.