We saw Blizzard's first April Fool's Joke in this post. Now here's another:
We are treated to a whole Wisps-Are-The-Alliance-Race-writeup including:
(Okay, so maybe I added the "Patch," and I stole your bandwidth to do it too.)
p.s. There was also this Press Release on BurgerCraft for more than just WoW April Foolin'.