Indeed, finding the remnants of Saddam's chemical weapons will take weeks... possibly even months. But we knew that anyway, Blix told us as much!
What has been clearly demonstrated is that Iraq did not have enough of a coherent weapons programme to deploy or use them, or thus to pose any significant threat to its neighbours or the US or UK. What there was has probably been mostly bombed or 'inspected' away over the past 12 years.
At least with Iraq as an isolated, pariah state, hated by all, including extremist Islamist terrorists, the remnants of WMD were to some degree contained. Now where are they? Syria? Al Quaeda? Who knows?
Of course, this is a bit of a self fulfilling prophecy... Iraq's WMD could fall into terrorist hands, and the chosen strategy has probably made that all the more likely, thus providing justification for further action in the future.
In summary... I believe that, in the fullness of time, some remnants of WMD will be found in Iraq. I also believe that some other remnants will by now have been spirited away into Syria or elsewhere, or to terrorist groups. Unfortunately, now we have embarked on this aggressive, pre-emptive interventionist strategy, it is difficult to see where it will stop. Based on the Bush / Rumsfeld rhetoric, I fear Syria is next.