Call of Duty Files has a question and answer session with Todd Alderman lead designer of CoD2. An interesting read and a game that I for one can't wait for.

Battle chatter is a new feature special to Call of Duty 2. Your squadmates will tell you where the enemy is and what they are doing in real time. The sheer volume of voice included in Call of Duty 2 is staggering -- we've recorded over 20,000 lines of dialogue. Squadmates will tell you things like 'Enemy on the left, top floor!' or 'Behind that low wall!' all in real-time.