As of March 19, Call of Duty: World at War's first map pack was made available. For 800 Microsoft Points or $9.99 on PSN, you get three new multiplayer maps and a new Nazi Zombie map. I've purchased and played through each map for more details.
Station
The first map was located in a destroyed underground subway station. Located in the middle of the map are a few trains, with a blown out roof, creating a small hill of debris for players to run up on top of a train for a better vantage point. However, you are right in the open, exposed from all sides. Yeah, it's best not to stay there for very long.

You’re able to travel through the twisty corridors on either side of the map. You will quickly learn that Station is not a map to camp on. You need to always keep moving or sneaking up behind enemies. The map is essentially a number of bottlenecks leading to a large outdoor area. You will never feel safe.
Nightfire
Nightfire takes place in a bombed-out section of Berlin’s city streets, Nightfire definitely feels more “vertical” than the other maps, because besides the alleyways and streets we could duck down, there were a number of buildings to hide in or climb to find a sniper position.
Being in the streets can mean instant death and it’s incredibly easy to walk into a building and not notice the enemy huddled in the corner with a shotgun. Snipers will feel at home here.
Knee Deep
Knee Deep is a large island map featuring Japanese huts, flooded trenches, industrialized buildings, and tall grass. Expect lots of tactics from camping to keeping in motion. This map favors all kinds of play styles.

I found Knee Deep to be the prettiest of the new maps because the map is set during the day and isn’t oppressively grey like the other maps. The variety in the level design alone makes Knee Deep pleasing. Expect to be playing this map repeatedly.
Zombie Verruckt
This map is based on World at War’s Asylum level and adds small changes to the popular Zombie Nazi mode. In the original Zombie level, you earned points by killing zombies, which you used to buy new weapons, repair windows or remove obstructions to move upstairs. All of those still apply, but there’s now an added goal to this level.

Players start out on opposite ends of the building and must earn cash to reunite in the middle of the building. You’re also fighting to activate a generator, dubbed the “electroshock defense system”. Wait until a group of zombies get near this and you can let out a charge, killing them instantly like a giant bug zapper.
You won’t earn money by killing zombies this way, but you will save ammo and you will survive longer. And when your goal is to stay alive, you probably won’t be mourning the loss of money too much.
The other cool thing about this new map is the option to restore power to the various vending machines spread throughout the asylum. Spending your money will get a soda that gives you a perk, like Sleight of Hand, Juggernaut or Double Tap. Sadly, those perks only last until you’re taken down by a zombie.
Overall, found this map pack to be quite enjoyable and well worth the money. A must buy for any fan of the game.