This is one of the stranger World of Warcraft mentions out there -- WorldofWar.net spotted a posting on overclock.net that shows a Microsoft presentation to Best Buy employees mentioning our favorite game. Apparently WoW is a selling point for Windows 7, specifically when comparing the OS to Linux. If Best Buy wants to sell operating systems that play "the games your customers want (e.g. World of Warcraft)," then Windows is supposed to be the way to go.
Interesting. Then again, World of Warcraft is a big game, so you can't blame Microsoft for jumping on its popularity while trying to sell OSes. But it's a little misleading -- of course Blizzard has supported Apple's OS X on the disc from day one, and while they don't officially support running the game on Linux, it's certainly possible to do. If you really are going to buy a new OS, playing WoW might not be the best criteria to base your purchase choice on.