Yeah, Rumsfeld has already blown the whistle on that one. He took care to remove any use of the phrase "Mission Accomplished" in Bush's speech itself. He told Bob Woodward in 2006: "I was in Baghdad, and I was given a draft of that thing to look at. And I just died, and I said my God, it's too conclusive. And I fixed it and sent it back... they fixed the speech, but not the sign."
What strikes me, with my TV broadcasting degree, is the low angle of the camera. And the wide angle of that shot, that manages to include the sign. The President is never covered from such a low angle, more at eye-level, and usually more tightly framed. The camera was deliberately angled to include that infamous banner, the intended connection as clear as day.
And I'm not sure how often a very professional banner like that is prepared when a ship returns from a mission, even a combat one. And placed exactly there, as a backdrop. Perhaps our Navy veterans here can comment.