Hi again, Dahlia,
I am not arguing that the Geneva Convention does not apply to any of the Guantanamo detainees, mainly because I can see already that the national conversation on this runs the risk of reducing the issue to a narrow legal matter—witness yesterday's rather dismissive comment from President Bush that the issue is all about "legalisms." I am arguing that it's worthwhile to puzzle out what rules of warfare should apply to the present and related topics brought on by the post-9/11 world. And I believe they suggest a bright-line distinction between people covered by an ideal code of warfare and those who are not: whether or not they target civilians. If not, then they're protected. If so, then they're not. (They would in the latter case still be entitled to humane treatment, just not to the full-bodied protections afforded to POWs.)
You wondered where in settled warfare law I'm finding this no-targeting-civilians emphasis. Well, the Hague treaty on land warfare (in force since 1900) doesn't go more than a few words before stating that its purpose is to serve the interests, not of soldiers and sailors, but "of humanity and the ever increasing requirements of civilization." And in all four modern Geneva Conventions, the first class of people identified as entitled to protection are not military personnel, but all "persons taking no active part in the hostilities." And if it's a title you insist on, then the one for the Fourth Geneva Convention (signed by the attending nations the same day as the one covering the rights of POWs) should fit the bill: "relative to the Protection of Civilian Persons in Time of War."
So while you are right to say that the laws of warfare aim to inject minimal decency into how warriors treat each other (unlike you, I don't think this aim is a priori unrealizable), it's clear that this is not their only function, nor, given the textual placement priorities mentioned above, their most important one. There is also the more fundamental project of injecting minimal decency into how warriors treat the rest of us. In the game of war, the pawns need more protection than the knights.
And there is another, perhaps more important, non-textual reason for saying this: If fighters can be encouraged to focus their lethality on other fighters, then innocent lives gain protection. This is true even if often in warfare, many of those in the armies are also in a profound sense innocent (because their country was attacked or because they were conscripted). And anyway, in this war, given the levels of Taliban/al-Qaida belligerence, it's clear that most of the innocents, in Afghanistan and in the United States, are noncombatants.
You would reject my emphasis on civilian-protecting rules of war because "most wars—or many actions in many wars—ultimately target civilians." That view ignores the latest phase of modern warfare. Although modern wars (starting, most historians agree, with the American Civil War) introduced the ability to widely punish the general civilian population, the latest technological developments provide the ability to reverse that trend. It seems to me that in the special ops/guided munitions war in Afghanistan, the percentage of total casualties who were intentionally targeted civilians is, for a modern war, historically low. Question: What would be a good reason for armed combat to continue to develop in this fashion, as opposed to reverting to Dresden? Answer: If the rules of war that governments acknowledged emphasized protecting noncombatants.