First Strike

First Strike is an upcoming downloadable content package for Call of Duty: Black Ops. It will include four multiplayer maps and one zombie mode map. It will be available February 1, 2011 for Xbox 360. It will cost 1200 MS Points ($15.00). PS3 and PC users will have to wait until March or April to purchase the map pack. All four multiplayer maps have been confirmed to be interactive, like the doors on Radiation.

Berlin Wall
Berlin Wall is a fairly large map, set around Check Point Charlie. It will feature a "no man's land" between the walls, with auto-turrets watching over it.

Discovery
Discovery will take place in an old German base in the arctic, presumably based around Project Nova. It will feature a chasm crossed by a narrow bridge, destroyable with explosives.

Kowloon
Kowloon will be based around the mission Numbers, and has a zipline for rapid movement, similar to the zipline found in the first campaign level, Operation 40.

Stadium
Stadium will be a map based around an empty hockey arena. Not much else is known.

Ascension
The new Zombies map features the original WWII-era characters. It will have new weapons, perks, and space monkeys that steal the players' perks.

Wii
The instruction booklet of the Wii version includes there will be a "Shop" feature. It will have: "all downloaded content includes new features and maps". Wii Points are used to purchase map packs and are transferable to an SD Card.

The fact there is a downloadable shop feature on the Wii version, most likely indicates First Strike will be coming to the Wii version.

Videos
Video:Call of Duty: Black Ops - preview First Strike Multiplayer