Minecraft wiki entry for Development_versions, associated text: Burning mobs have a sizzling particle effect once extinguished
Mobs will now drop experience when killed
Zombie
Zombies now wear different armor and can hold items
Zombies now drop weapons and armor rarely
Skeletons
Skeletons now wear different armor and can hold items
Improved accuracy
Skeletons now drop weapons and armor rarely
Spawning Skeletons in the Nether have a chance to spawn as a Wither Skeleton
Slimes
Now have particles when jumping
Now drops slimeball
Magma cubes
Magma cubes and Ghasts now spawn naturally
Magma cubes now split when killed
Zombie pigmen
Zombie Pigmen are now neutral
Now spawn in the Nether
Villagers
Can now open and close doors
Can now harvest crops
Can now breed
Now has angry particles if attacked by the player