A reliable source close to the Call of Duty development teams has revealed not only the existence of Call of Duty 4, but vital details surrounding the game as well, including the fact that it will be based on modern combat.
According to our source, Call of Duty 4 will be developed by Infinity Ward, the developer behind the first and second installments. The three-way deal established between Infinity Ward, Treyarch, and Activision states that Infinity Ward will develop all even numbered titles while Treyarch develops the odd numbered games, such as Call of Duty 3. Treyarch did develop Call of Duty 2: Big Red One as well, however.
As aforementioned, Call of Duty 4 is said to step away from the war torn locales of World War II, instead focusing on the battlefields of present day. It is unknown if it will take the same path as Electronic Arts' Battlefield franchise, placing the spotlight on the Middle East.