Matt Yglesias hardly needs linkage from me; not only is he one of the stars of the left-leaning blogosphere, but Atrios already linked to this article for Pete's sake (and had some good things to add to it, too, though you should read Matt's piece first). But Matt Ygelsias's latest article in collaboration with Sam Rosenfeld, about the current argument of liberal hawks that the problem with the Iraq war was that it was incompetently executed, is simply superb, and gets at why many of us opposed this !@#$% war in the first place, even knowing full well that Saddam Hussein was a monster.
After slicing & dicing the liberal hawks, Yglesias has George Will for desert here. But eat the main meal first: it's the important bit.
Update: Not that I agree with everything they say; in particular, I'm sure their criteria for when interventions will and won't work can be debated and improved on. Still a must-read though.