Minecraft Snapshot 13w01a released, possibly the biggest snapshot yet

This week is the first snapshot of Minecraft 1.5, and boy is it feature-packed. The first addition is the daylight sensor we covered yesterday, which acts like a redstone solar panel. Also new is the Hopper, a new redstone machine for placing items into chests/furnaces (similar to pipes in Tekkit). Trapped Chests are brand new, that when opened put out redstone signals on all sides. Redstone Blocks are blocks that act like a torch, but can be moved with pistons. The first-ever Nether Ore, called Nether Quartz Ore, has been added and can be mined with any level of pickaxe. More features include slight changes to the inventory and lots of bug fixes. This might be one of the biggest snapshots of all time, and you can get it at Mojang's website.

Source: Mojang