There will be new Downloadable content for Call of Duty 4 : Modern Warfare which should be scheduled for release on spring as announced by Activision. And also watch out for downloadable contents for the Xbox360 and PS3 as well as new multiplayer maps and such.
News From IGN

New downloadable multiplayer maps are on the way […]

A part of the Xbox Originals promo recently brought to us by Xbox Live Anninversary, There will be three new games available for download straight to your Xbox 360 Hard Drive for the price of 1200 Microsoft Points, you have chance to download Ninja Gaiden Black, Sid Meier’s Pirates! and BLACK on the Xbox Live […]