Here’s the development snapshot of week 7, 2012! List of changes:

    Added new world file format called “Anvil” (256 max height and 4096 block IDs*)
    Multi-player light calculations do no longer cause affected blocks to be transmitted to the clients, instead the clients will recalculate the light on their own
    Villagers will repopulate villages based on how many houses there are available
    Some nights in villages will be worse than others…
    Added a redstone-controlled light source
    Decreased chance for the rare mob drops
    All animals use the new AI system now

* The game can’t use the full range of IDs yet because there are still some assumptions that IDs above 256 are items.

Update! New version number is 12w07b, fixing the following problems:

    Crash bug corrupting levels when spawning mobs above the 255th block
    Sheep animation is correct in SMP

Get the snapshot here:

    Client: http://assets.minecraft.net/12w07b/minecraft.jar
    Server: http://assets.minecraft.net/12w07b/minecraft_server.jar