^^Yea, I downloaded the demo last week. I loved the old one. New one seems pretty cool. Hard to tell from a demo.
lotz - Yes... well kind of.. The real answer is - There isn't really a 3rd zombie map. That blank space is reserved for dead ops arcade (check your achievements, you'll see two for it.) I JUST found this today. It's like a classic NES game where you kill zombies.
****SPOILER ALERT****
When at the title screen, when you're sitting in the chair.... look down at your hands and press RT and LT repeatedly to break free of the restraints. Go over to the computer and use it. First type CD. Then type DOA
*****END SPOILER******