This is the first snapshot that contains features for the coming Redstone Update.

Redstones circuits are more consistent and pistons should be more stable
Added the Redstone Comparator block (this replaces the Capacitor we talked about at Minecon)
Added the Daylight Detector block
Added a Hopper block (still work in progress)
Added a chest that activates redstone
Added weighted pressure plates that detect item stacks
Added Block of Redstone block (works as a pushable redstone torch)
Added a new ore to the Nether
Added a Nether Brick item for crafting Nether Brick blocks
A whole bunch of other stuff... Try for instance double-clicking items, or drag-placing them, in the inventory

Get the snapshot here:

Client: http://assets.minecraft.net/13w01a/minecraft.jar
Server: http://assets.minecraft.net/13w01a/minecraft_server.jar (or EXE)