The article breaks it all down into 3 groups: al Qaida in Iraq, headed by Zarquai, hardcore Baathists, and non-hardcore Baathist sympathizers. It’s all very good reading, most particularly the goals of the hardcore Baathists, which are to regain control of Iraq should the US leave. They thing they have the capability to do so based on their superior organization and ruthlessness.
All of which makes me wonder, the US death rate seems to be holding at around 15 or so per week, with a variance of 5 or so. However they seem to be coming in offensive action, not random murder, and the number of insurgents killed has been skyrocketing lately. Hopefully this is a good sign.