"Seems to me that arguing over whether it is legal, or legit is a pointless exercise unless there are some real consequences for breaking international law in this way."

Well, for Blair it could make a difference, since he hasn't managed to get an opt out from the International War Crimes Tribunal for himself and for those following his orders. He could get arrested. And the same would apply particularly to his friend the Prime Minister of Italy, Berlusconi - the courts in Italy are already after him for financial shenanigans, because there are Italian lawyers and judges with guts.

And, in principle, it could make a difference for Bush, if the US courts and legal system do their job. He might have got out from under international courts - but, if this war is illegal under international law, it's illegal under US law, since the United Nations Treaty was formally adopted by the USA, and therefore surely has legal status in the USA.

If it's an illegal war, that means that a crime is being committed, and it must be someone's duty to prosecute those who appear responsible for this crime. After all, one reason given for the USA excluding itself from the International War Crimes Tribunal was that US law could be relied on to deal with cases of war crimes alleged to have been committed by US citizens.

Mind, I wouldn't hold my breath. I imagine it's about as likely that the US courts will see such a prosecution as it is that anything like that will happen in an Iraqi court to Saddam right now. And even when there's been a regime change in Washington (touch wood), I imagine it'll be a question of "you scratch my back, I'll scratch yours".