I may be a bit late on this, but there's a new pack of maps coming out May 3rd for COD: Black Ops.
It's called Escalation, and includes Zoo, Hotel, Convoy, Stockpile and a new zombie map.
Preview
I think it looks good, better than the first strike pack, anyways.
They say they wanted to get more variety in the multiplayer maps. They have alot of interactive items like elevators and garage doors, which should be pretty cool.
I also wonder why there is such a huge gap between the 360 release and the release for other consoles. Why don't they just release it all at once?
EDIT: The preview says that there's all new zombie characters. That should be neat.