ianmacd: I think the US should be part of the international criminal court as well, but from what I have read, it really needs to be, at least initially, for the worst of the worst - rape, torture, genocide, stuff like that. As much as you (or I) might not think this war is a good idea, you can't be taken seriously if you think that that is condoned by US leaders. By declaring that Bush and company should be dragged before the ICC, you play right into their opposition to US involvement in it, because you would use it for what amounts to political purposes, and that's why they say the US shouldn't participate.

As to the illegality of the war, that's a different matter from war crimes. The Economist has an interesting article on the issue, at http://www.economist.com/printedition/displayStory.cfm?Story_ID=1649850 although unfortunately it's "premium content". A relevant quote:

It is not yet clear whether the United States is proposing to ditch the whole idea of international law, or merely to revise its rules. Many statements by Mr Bush and other senior American officials seem to indicate the former.