According to CNN, Anbar and Salaheddin provinces, overwhelmingly Sunni, overwhelmingly voted no. The rest approved it. If three provinces had voted it down, it would not have passed.
I have to say, the fact that the vote was mostly along ethnic / religious lines bothers me. With some others, I think it might have been better if it hadn't passed. If the Sunnis saw their vote change this, then maybe they would be more willing to give democracy a chance in the future.
That aside, that's a job well done for the Iraqi government, and kudos to the Coalition and Iraqi forces for the security that allowed it to happen.