I was playing the Cataclysm beta last night and we got a group together to go kill this giant whale shark. It didn't drop any loot but it one shot anyone and had an insane amount of HP. We kited it around with a Death Knight tank spamming Icy Touch until we finally killed the beast! Got an achievement and it was a pretty fun time.
Sadly, the whale shark was a little glitchy (it's hitbox was off a bit and it's animations were a little iffy)