The latest snapshot is pretty cool. Here are some of the more major additions:
- A new ore! More specifically, emerald ore, which yields...emeralds.

These can be traded with the villagers for items like enchantment bottles.
- Sandstone stairs (although unfortunately they can't be crafted yet).
- A new golden apple recipe. You can use blocks instead of ingots, but when you do the apple will give you health regeneration in addition to fire resistence and general resistence for several minutes afterwards.
- Villages in the desert have a new look:
- Speaking of new structures, you can now find pyramids in the desert:
- Gravel has a new texture:
- There's also a new block called the "Ender Chest."
They function like normal chests, with one exception - their contents are stored across all Ender chests, meaning that if you place an item in one such chest, it'll also appear in another. This is a useful way to teleport items back to your home base.
Be careful though...apparently there's a bug causing your old world to become corrupted if you load it with this latest snapshot, so make sure you start a new world if you want to try the snapshot out.