Minecraft wiki entry for Development_versions, associated text: The famous high-distance world rendering offset bug has been fixed (except for moving pistons)
Redstone repeater top faces are no longer weirdly broken
Rails, powered rails and detector rails are no longer stretched
Ladders are no longer offset nor stretched
Upwards travelling redstone wire no longer appears offset from the block it's on
The side faces of flowing water and lava are no longer broken