Blizzard is notorious for playing pranks on its customers on April Fools' Day, including the pandaren as a fifth race in Warcraft III, the 2005 "Burgercraft" fast food chain idea, and the two-headed ogre and wisp racial ideas in WoW. My personal favorite is Caydiem's "Evil Patch Notes 1.11", which is still one of the best pieces of WoW satire out there.
Now, as the end of March quickly approaches, we have to wonder what Blizzard will pull this time. They have a lot of options. How about "The Great Sea" expansion, which would be entirely underwater? Better make friends with some warlocks and shamans quickly. Or an announcement that due to "overly rapid raiding progression," all trash mobs in Karazhan, Serpentshrine Cavern, and Tempest Keep will have their HP and numbers doubled? It would be neat to have some in-game changes, but that's unlikely. I'd love a joke where for one day, you have to CHANGE history in the Caverns of Time and see that the world would actually be a better place if you killed Medivh or Thrall. Then the next day, whoops, back to preserving the timeline!
What do you think Blizzard is going to do for April 1? What sort of pranks and tricks do you think would be neat to see?