Steven Den Beste has a must-read analysis of the new interim Iraqi Constitution. This is an academic-quality piece of work. Steven uses a dichotomy between semantic and structural clauses to illustrate how any given constitution is able to react to long-term changes, and points to the prevalence of the former in the EU Constitution and the latter in the U.S. Constitution to make the point. Armed with these concepts to aid the analysis, he takes a look at the new Iraqi document.
The bottom line is that the interim constitution has an innovative approach to the problem of the ethnic divisions within Iraq, which promised to be the major obstacle to ratification and implementation. The two great innovations of the US Constitution were 1) setting the Judiciary as a separate and co-equal third branch of government, and 2) using a bicameral solution for the Legislative Branch to solve the big-state/small-state problem. In the Iraqi Constitution, the great innovation relates to the Executive Branch (and doesn't bother with a bicameral legislature) because the fundamental problem is ethnic, not demographic.
However, the problems that the innovations in 1776 and now 2004 were designed to solve stem from the same basic cause, namely the fear of tyranny of the majority/minority by the minority/majority. As Steven explains, the Iraqi interim constitution achieves an elegant solution tailored to the Iraqi reality of ethnic division, without actually making explicit semantic reference to ethnicity. (go read it!)
It's also worth noting that this is an interim document, but the permanent Iraqi constitution will be largely based on the precedent set by this one. The goal is to establish stable governance, and not let that goal get sidetracked by the allure of perfection. Perfection is the enemy of the good.
It's hard not to be optimistic about the document, but it's important to note that a constitution is just a piece of paper. In 1776 there were not terrorist attacks against religious targets and civilians to contend with, and the colonies were relatively isolated from external forces after winning the war (compared to Iraq).
I also think that the Bush Administration's planned handover of sovereignity, and massive troop reductions shortly afterwards, are going to work against stability in the long term. There is a real void in terms of civil order that our troops are unable to fill, and into which destabilizing Shi'a militias are stepping forward. The political-deadline-driven handover is going to be a massive obstacle to giving this new constitution a chance to become part of the landscape.
Overall, I am still greatly pessimistic. But the new constitution has allowed me some hope that things may yet evade the facts on the ground.