After Robert Bowling, Community Relations Manager at Infinity Ward, posted a bunch of concept box arts for Call of Duty 4 for the community to vote on, it was noticed that the covers had "Storage Required" labels on them and thus reports went out that COD4 would require a memory card or hard drive. MyGamerCard.net asked Robert about the matter, and he had this to say:
The Storage Required icon should be disregarded. It was simply included as part of the concept artwork by the artist, to give a better representation of what the final box art would look like with icons and logos on it. The game can still be played by users with and without Storage devices (HDD / Memory Card). Obviously you can not save if you are without storage, but that goes for every Xbox 360 title.