In case anyone's missed it, this Josh Marshall post is worth reading. During the run-up everyone's favorite quagmire on the Tigris, apparently, an Iraqi foreign minister had defected and told the CIA that Saddam Hussein had no WMDs. But the White House took no interest in all of this; a non-existent weapons program doesn't exactly bolster the case for war, after all.
But the remarkable thing here is that none of the authoritative-sounding commissions that investigated whether the prewar intelligence was botched or mishandled or distorted looked into this incident. Or rather, they were told about it and ignored it entirely.