Blizzard is always fighting a quiet war with World of Warcraft dataminers who scoop info out of the game files that they aren't always supposed to see yet. These days, the discoveries are relatively minor, but they can still hint at future updates that haven't been announced yet.
During the alpha and beta testing period for the Midnight expansion, players found an island that wasn't accessible by normal means and would kick you out if you stepped foot on it. That area, Atal'Utek, is still around in the final release and more players are starting to realize that there's something fishy going on with it.
