Taken from That VideoGame Blog
“Call of Duty 7” is in production, which the war takes place in the “Vietnam War”.
The set of the war is said to be a Cold War. Activision is looking to licence music for “Call of Duty 7,” Soviet Union, African and Cuban music installed in the game.
There are no other details offered on the game. It is assumed to be release on 2010.
While, Call of Duty 6 or Modern Warfare II is going to be release on November 10, 2009.