Just to get you ready, here's a quick roundup of what they've done in the past few years. It seems like they've been upping the ante for a while now, so be "prepared": you never know what we might hear from them tomorrow.
2004: Blizzard announced that two-headed Ogres would become a playable race... playable by two players, that is. Not many people fell for this one -- MMOs are all about being social, but playing a character with another player? A little too wacky to be legit.
Lots more after the break, including the chaos that went down last year (Tinfoil Hats, anyone?) in the Warcraft community.