http://www.mojang.com/2012/05/minecraft-snapshot-week-22/ just basically lists and allows you to download what is going to be on the latest update you're now able to trade with villagers which i think is a great idea!
they've added some really good features in! if you find emeralds you can trade them with villagers for bread, they've added new things like ender chests and trip wires
we should make a adventure server lol omg lvl 30 enchantment is awesome oO omg wtf, u gain massive xp by destroying blocks & wtf this game is now overpowered xDD
There is a mod that can do that. MCNostalgia. There are instructions that tell you how to take Minecraft back to any past version. From the last version, 1.2.4 to the very first Alpha release.
I don't wan t a mod though, They contradicted the main essence of the game, Isolation, by adding npc's; they put shit in that they don't need.