New possible maps set to be released September 9th 2011. The map pack name is Retaliation.

Multi-Player Maps:
Mansion
Cargo
Metro
Harbor

Mansion takes place in Castro's secret compound in Cuba.
Cargo takes place in an frozen shipping center in Greenland.
Metro takes place in an urban city in Vietnam.
Harbor takes place in an abandoned shipyard in America

New Zombies Map is set to take place in Area 51. The map is called Quarantine.
The map pack will also include a new Zombies map titled Quarantine, set in Area 51, the highly controversial military base in Nevada.

This info was posted on the same website that leaked all of the other map packs. IT was on for 20 minutes then deleted by activision.

F-irst Strike
E-scalation
A-nnihilation
R-etaliation

Maps are 1200msp.
9.6.11