Via Nobody's Business, Rogier Van Bakel notes that the Mission Accomplished banner under a speech given by Bush over three years ago has been crudely cropped from the video. Check out Bakel's post for links to the video.
Update: It looks like the 'blocked out banner' has been debunked. Good old internet. Gotta love it. It appears that the blacked out portion was from network (CNN) ticker programming being eliminated. The banner itself was up high and behind the president. Click the link noted above to see the commentary on this issue at Bakel's blog.