Speaking at their PAX Prime panel, Jeb formally named the latest Minecraft update after Nathan "Dinnerbone" Adams' suggestion. Its decorative features, combined with a new monster and release date "around Hallowe'en," will make it the "Pretty Scary Update."
The four person panel didn't reveal many new secrets about what to expect from Minecraft 1.4 or beyond, but, after a correct guess by a member of the audience, they said that the new boss monster, the Wither, can be summoned by combining three skeleton heads, which will be a new monster drop.
Jeb also talked about his reticence to further alter the biome and terrain generation algorithms, even though it's "One of the things I get the most feedback on," as this can affect the seeds players use and share for world generation, and said that though he was interested in adding more mechanical elements and moving parts to the game, this is challenging because "Pistons are the feature that'd have the most bugs." That said, the new API that 1.4 will introduce should solve a lot of technical issues with the game.
The team also got technical, saying that they're optimising their code all the time and gradually trying to move some of the work that your CPU does over to your GPU, and explained that the PC and Xbox versions of Minecraft are likely to further diverge, with each having its own distinct features, one reason being that the Xbox version cannot match the PC's regular updates.
You can watch the full panel, hugs and all, here on Twitch TV. It starts a little after 3:05:00.