Minecraft wiki entry for Pretty_Scary_Update, associated text: 5 new commands: /difficulty, /spawnpoint, /weather, /gamerule, and /clear.
New command target selectors.
New sounds for mobs, walking on blocks, placing blocks, climbing ladders, and more.
Witch huts
10 new blocks: command blocks, beacons, anvils, flower pots, cobblestone walls, item frames, mob heads, wooden buttons, potato crops, and carrot crops.
9 new items: potatoes, poisonous potatoes, carrots, golden carrots, carrot on a stick, pumpkin pie, nether star, potion of Night Vision, and potion of Invisibility.
5 new mobs: the wither, wither skeletons, witches, bats, and Zombie Villagers.