|The new Snow Man seems like a nice guy|
The Nether is getting a facelift including new mobs, new blocks generated structures such as ruins and more. The new creatures added are Magma Cubes which are just Nether skins for slimes, Blazes are humanoid monsters that float in the air and throw fireballs, and Snow Golems are craft-able companions who will follow you around and annoy the mobs around you.
The additions made are obviously more preparations for making Minecraft more of a game with some kind purpose or goals and the team at Mojang seem to speeding up process of releasing updates before the game's release in November.
There is still no word on when this release will be become official.