It appears as if it’s finally been settled. According to an update from Infinity Ward community manager, Robert Bowling, the upcoming Modern Warfare 2 from Activision and Infinity Ward will retain the branding of the popular Call of Duty series, making the game Call of Duty; Modern Warfare 2.
“Just recieved the first Modern Warfare 2 boxes straight off the press.” wrote Robert Bowling in his update. “Shit just got real.” He provided a link to an image of the official Call of Duty: Modern Warfare 2 box art, which yes, featured the Call of Duty branding.
End of story.