This isn't quite the smoking gun of WMD for this particular reason for war. They are pre-1991 weapons.
First of all, aside from these warheads, it is clear that Saddam was prepared to produce chemical and biological weapons when sanctions eroded. Even nuclear ambitions remained.
But the old chemical warheads are significant. One, they prove that Saddam did have WMD in violation of his obligations under UN Security Council resolutions. This is the technical violation of his parole to go along with the more significant production capabilities Saddam retained hidden as dual-use facilities and components that Iraq War opponents disregard.
And two, it shows that it is possible for Saddam's people to have hidden more recent chemical weapons in the vast regions of Sunni-inhabited Iraq. These weapons have been discovered over the last couple years, so more could be out there, buried in the desert.
I'm still waiting for conventional wisdom 5.0 on Iraq's WMD:
This groupthink that Saddam had no WMD in March 2003 replaces the conventional wisdom that Saddam's scientists were all bluffing a psychopathic mass murderer by pretending to have WMD programs; which itself was a replacement for the theory that Saddam was purely bluffing all of us. And this, of course, replaces the conventional wisdom held by both parties for nearly a decade that Saddam had WMD in defiance of UNSC resolutions demanding he disarm.
We'll find the WMD yet or what happened to them. Mark my words.
This version is getting closer.
