The Xbox 360's timed exclusive on the Escalation map pack for Call of Duty: Black Ops is coming to an end in two weeks' time. Activision has announced the DLC will be released on PC on June 2.
The map pack contains four new competitive multiplayer maps and a new Zombies mode map, Call of the Dead, which features the likenesses of several famous actors. 1UP played the DLC earlier this month for Game Night, which you can watch here and here.
There is still no date for the PlayStation 3 version of the map pack; it will have to wait at least until the PlayStation Store comes back online, currently rumored to be happening next Tuesday, May 24. The PC version is already available for pre-order on Steam, where you can currently get it for $13.49 instead of the usual $14.99.