New Skeleton variant in the the Nether
New Obsidian Block
New Wither Boss Picture
To spawn the Wither Boss-You need 4 SoulSand blocks placed in a T formation and you place 3 Wither Skull on the three blocks on the top part of the T.
I've never tried using a snapshot before and I've stayed on 1.2.5 after hearing of all the problems with 1.3.x
Is it really just as simple as swapping out the .jar files? If this snapshot has problems do I just replace it with my old (stable) 1.2.5 jar and everything will be back to normal?