Yesterday, Minecraft Snapshot 12w03a was released, introducing the first set of changes since 1.1 was released last week. Some of the changes included updates to the game's language files, changes to creature AI, and an all-new jungle biome.
In case you missed it, check out the official changes here. But in the event you have downloaded the patch and haven't experienced the brand new biome, lead developer Jens "Jeb" Bergensten posted a teaser image of the new biome on his Twitter, shortly before they released the snapshot.
Currently, it's just filled with green blocky leaves of jungle goodness, but if the fellow developer @Jonkagstron has his way, there will soon be some animals added to populate this new biome.
Blocky monkeys and tigers anybody? I also think they need to add Baloo….just because.