Minecraft wiki entry for Development_versions, associated text: Nerfed iron golem spawn rate.
Fixed bug with updating powered rail when placing redstone.
Fixed stairs being placed upside down when placed on snow.
Fixed not being able to put torches on upside-down stairs, probably normal stairs too.
Fixed jukeboxes not playing above level 128.
Fixed not being able to grow huge mushrooms above level 128.
Fixed bug with growing trees above level 128 with bone meal.
Fixed crash bug with iron golem building.
When building an iron golem, the block above them is no longer destroyed.
Fixed tamed wolves still attacking sheep.
Fixed some language bugs.
Fixed some Anvil bugs.
Fixed the client not properly handling biome values greater than 22.
Fixed mobs spawning half as quick due to the code checking in invalid spawning places half of the time due to the new world height.
Fixed lava lakes generating over bedrock.
Fixed iron Golem's texture being white or invisible.
Fixed the iron Golem model.
Fixed villagers being restless at night.
Fixed nether wart dropping from soul sand.
Fixed lag from iron golems.
Iron golems no longer drown.