William Lind has an article in The American Conservative with a provocative proposal about Iraq that, I think, manages to highlight the extent to which a lot of the Iraq discussion has become misguided. Lind's basic idea is that we should make some kind of accommodation with Iran, get our troops out of Iraq, and hope that Muqtada al-Sadr (or perhaps and equivalent populist, anti-American Shiite) takes the country over.
As it happens, I agree with Lind that this would be an okay outcome given the realistically possible options. One must see, though, that to many American observers "limiting Iranian influence in Iraq" is a top-tier priority. The way Lind sees it, our top priority is just that someone or other effectively control Iraq territory so that non-state actors (i.e., al-Qaeda) don't run free. The point, though, is that you can't talk about which plans will "work" for Iraq unless you talk about what it is we're trying to accomplish in broader regional terms. The "check Iranian influence" theory is very, very popular in Washington and, I think, is most of what's actually motivating the "residual forces" crowd. But the disagreement there is about broader strategic priorities and not about Iraq as such.
Defense Department photo by Master Sargent Jonathan Doti, U.S. Air Force