It was known by many that “Call of Duty” name was chosen to be dropped from the sequel to Call of Duty 4: Modern Warfare. Now, it appears that the name was been propped back up, as the boxart has been revealed.
Robert Bowling, aka fourzerotwo, has posted the official boxart of what the game that was originally referred to as simply Modern Warfare 2. Bowling posted them on his Twitter account, and stated that they were the first Modern Warfare 2 boxarts. Apparently, the lack of brand awareness may have talked Activision into changing the moniker.
[Source]