EDIT: Dangit, can a mod move this to recent updates and snapshots? I messed up.
Disclaimer or whatever you wanna call it: I have not seen any topics on this. I searched it, too. So if there is one, forgive me.
Many of you may not know, but Dr. Zhark and the Mojangstas added something hidden in the new snapshot. Zombie and Skeleton Horses!
What do you think of them? Could this mean Zombie Jockeys? Or a Skeleton Jockey? (Not to be confused with Spider Jockey)
They can also be seen in this video, by GameChap:
As you can see, they don't do much yet. They don't even burn. What will Mojang do with this undead creatures? I guess we'll have to wait and see!
With the skeletons new behavior and if it could ride those horses, it would be EPIC! They would have great aim, rapid fire, and now, the horses could try and avoid you! (Moving too fast for u to hit them but they can hit you) LOOK OUT EVERYONE! SKELETONS ARE GETTING EVEN HARDER! Yea that would be cool...
I love the Idea of Zombies and Skeletons mounting their own type of horse. I'm not sure it'd work too well for the Skeletons unless they made some changes to the AI, or better still wrote some AI specifically for mounts, otherwise he'd be up in your face doing very little damage. With Mojang working on Zombies spawning underground in larger numbers when they are attacked (I think that's how the changes are supposed to work), and the possibility of more mounted mobs on the surface, we may start to really get a feel of different atmospherics depending on where we are in-game.
Oh, Unicorns and Winged Horses are a no-brainer, Mojang would definitely be missing a trick if these never got added, even if not right away.