Quote from XSSheep
The 1.4 update changed the mob file for zombies so the zombie will only appear correctly in the snapshots/pre-release/1.4 update!
So basically, you're going to have to wait until tomorrow to have non glitchy zombies if you don't want to run the pre-release.
BTW - thanks for the update, Wayuki, it's awesome!
Quote from Wayuki
The format of the zombie skins changed in 1.4. This update is incompatible with 1.3.
So, to use the zombie skins, you will need the latest snapshot, or wait until 1.4 comes out in a couple of hours.
Also, to use Randomobs you will need to install MCPatcher.
EDIT: Ninja'd by XSSheep! XD
Thanks, both of you! I was just so excited my heart was a little chipped to see the broken zombies! If only I had waited one day, I wouldn't have even noticed! Now everyone else knows, at least.