The LA Times just published an in-depth article that does a splendid job of laying out the path to war and Plamegate's role within the larger picture. While it was beyond the scope of the article to cover the aluminum tube debacle, the Curveball debacle, and other details, this account does a splendid job of collating many previously established storylines into one coherent source.
This article is particularly good at the office politics angle. I must confess that the Bush administration often reminds me of the administration at a school where I once taught. There's a similar love of shooting-from-the-hip and going on instinct, a lack of curiosity and a disdain for planning, an anti-empiricism and a disappointing hubris. It takes a good leader to realize that respectful dissent is the ultimate sign of fealty, not disloyalty... Paul O'Neill's greatest lament with Bush was that he lacked "honest brokers" who would speak truth to power without a political agenda.
While some of the office politics in the Bush administration should seem familiar to just about everyone, the difference is that a turf war on this level can and does cost lives. The degree of professionalism and competence required for effective government at this level can be staggering. On this note, regarding Iraq, to hell with ideology for a moment - evaluate the Bush administration based on performance.
(Although registration at the LA Times is free, I've used a Yahoo link for the article instead for easier access.) Enjoy.