If one follows Sun Zi's doctrine (or that of von Klausewicz), military solution is just an extension of politics. So if one does not solve the more fundamental problem, which is political, even the best military solution treats only symptoms, not the cause.
W Bush now follows the second best (or second worse) direction as per Barnett's (sort of), which is a military, by increasing the size of the invading troops. (Barnett may not agree with this, as Bush only did half of what he suggested, by not leveraging on the international effort in the occupation)
We already have a conclusion on what would have worked and what failed, as discussed by Faheed Zakaria in Newsweek, who showed that a poitical problem requires a political solution.
The lesson of Iraq reinforces our believe that sometimes the apparently dumb and risk averse solution to a problem may be the most appropriate one. Here I am referring to the Gradualism (Feeling the stone to cross a river) approach by Deng Xiaoping. There are good reasons that there is probably no better way. Because these problems at the national level are so large and complex, and there are so many ways to get it wrong with so many variables from the beginning situation and as it evolves, that perhaps there is no other way than taking a self-correcting path and walk on it step by step.
Such solution only comes from humble minds. When one becomes over-confident, even a hyperpower like the US suffers its Waterloo. As China's GDP grows and people begin to talk about "Great Nations", "Bush in Iraq" serves as a good remind for President Hu, about Deng's teaching of Tao Guang Yang Hui.