Horse

Horses are a planned 1.6 mob hinted by Jeb when Minecraft hit 10,000,000 sales. In a later tweet, Jeb said DrZhark, creator of the Mo' Creatures mod is assisting with the horse's creation, which is most noted by Jeb's Instagram picture, that shows that the horse model is the same from Mo' Creatures. . DrZhark was asked if the horses from the mod will be the same as the ones in 1.6. He responded "What do you think?" You will be able to put armor on them and tie them to fence posts. The two screenshots released by Jeb suggests there will be different breeds of horses, similar to the different breeds of cats, though this has not been confirmed yet. Horses will be able to jump. Baby horses' growth can be accelerated via the use of apples, wheat, sugar, hay bales, and are completely passive when hit, unlike other mobs.

Breeds
There are 4 breeds of horses in the game. Some have multiple colors of fur but are still the same breed.

Horses and Foals
Horses are the regular horse breed in the game, and occasional foals will spawn too. They can wear horse saddles and can wear any horse armor. Foals can be fed apples, wheat and sugar to grow faster, however sugar grows them a little less than an apple.

Mules and Donkeys
Mules are a different variation of horses, and are less common than horses when spawned, and young donkeys and mules can be fed apples and sugar as well. They can wear a horse saddle, but not horse armor. Instead, they can wear a chest, but the inventory is not accessible.

Skeleton
The skin is found in the textures, but this is all that's known currently. It is a skeleton variation of a horse.

Undead
The skin is found in the textures, but this is all that's known currently. It is a zombie variation of a horse.

Taming
To tame a wild horse, approach it and right click on it with an empty hand. You will climb on top of it, and likely be thrown off. The taming appears to be sped up by feeding the horse any of the approved foods (apples, wheat, sugar, hay bales), but only whilst on the horse, before it throws you off. After a few attempts, it will let you remain on it. At this point you can dismount it by pressing Left Shift and place a Horse Saddle on it.

Riding
Once you have tamed a horse and put a Horse Saddle on it, you can control it with WASD and the mouse. W moves the horse forward, S moves the horse backwards, and A and D allow you to strafe left and right, respectively. Space Bar allows you to jump, and holding the Space Bar allows you to charge your jump (The maximum jump height is four blocks, allowing you to jump on top of any three block high structure). Moving the mouse left or right causes the horse to turn in that direction, while moving the mouse up or down allows the player to look up or down. Left Shift causes you to dismount, as does going in water deeper than two blocks.

When you mount a horse, the Hunger Bar and Oxygen Bar are replaced by the horse's health. It uses a slightly different heart texture than the player's Health Bar. The experience bar is replaced by the horse Jump Bar, which gauges how high you jump.

You can use any item while riding a horse, including drinking or throwing potions, activating doors or redstone devices, or using Chests, Crafting Tables, and Furnaces. You can also break and place blocks and attack. This also allows you to heal your horse with a carrot while you ride it.

When running forward, you will start at a slow walk and build to a speed faster than sprinting. You will automatically run up any one block high slope. You are three blocks tall while on a horse, but your head will pass through transparent blocks such as leaves or glass. It is unknown if this is a bug. You are slightly wider than one block, and are unable to walk through one block wide gaps. However, due to the horse's length, you can run over any one block gap. It also appears you can run across a two block gap at high speeds, but this does not seem to work all the time. You can also cause your horse to climb ladders by running at it similar to how players climb them.