http://www.vg247.com/2012/01/25/ten-new-maps-two-modes-coming-to-modern-warfare-3-this-year/#more-228592
According to a calendar on the Call of Duty website, players can expect ten new maps, six Spec Ops missions, and two new modes over the next nine months.
The first two drops – Liberation and Piazza maps – arrived on Xbox Live today.
The schedule, listed in full below, applies to Elite subscribers only; plebs have to wait for sporadic releases at a later date. All drops will launch first on Xbox 360, and then appear on PC and PlayStation 3 after an exclusivity period.
February: New map
March: New map, two new Spec Ops missions
April: Two new maps
May: New map, new Spec Ops mission
June: New map, new Spec Ops mission, new game mode
July: Two new maps
August: New map, new Spec Ops mission, new game mode
September: New map, new Spec Ops mission
Thanks, Eurogamer.