Newbie's right (for once).
To expand: the US military's largely organized around conventional warfare...large, heavy, organized units rattle-assing around a battlefield with defined (to a degree - the definition is never exact) front lines. A good example of such is: invading a country. So as such, when the invasion of Iraq was over, the President's statement was truthful, timely, and accurate.
The real issue was with the wording - "major combat operations", while accurate in terms of the intensity of operations, gave the implication that the peace that followed would be "minor" (accurate, again in terms of intensity) and hence "easier" (patently untrue, as anyone with half a brain pretty much realized). The problem with his statement was that most people will equate "major" to "more difficult", which is an incorrect inference that Bush's speechwriters should have known better than to foster.