I have long said that I thought that Zarqawi was more being used as a figure for us to focus our rage on then being the actual mastermind behind the insurgency (I don't think there is a single mastermind). Even if he is in some sense the "head" of the insurgency, he is probably mostly a figurehead and is in any case eminently expendable. While it is convenient to pretend that once we get him, Iraq will settle down, I think that in reality we'll just find someone else to focus on.
Sami of the Iraqi Thoughts blog appears to agree with me (for the most part) on this issue. Read the blog entry for some interesting thoughts.
That is all.