The so-called September Surprise from David Kay sounds like a dud to me. But, in this FAIR AND BALANCED account from The Guardian he lays out some of what we can expect:

The former UN inspector hired by the Bush administration to find evidence that Saddam Hussein had weapons of mass destruction will claim in a report next month that Iraqi forces were ordered to fire chemical shells at invading coalition troops, according to US reports.
But David Kay, who heads the 1,400-strong Iraq Survey Group, has admitted he has found no trace of the weapons themselves, and cannot explain why they were never used.

One possibility is that the orders were part of an elaborate bluff, in the hope that they would be intercepted by the US and deter an attack.

According to US officials, all the Iraqi scientists now in custody have insisted that Saddam's arsenal of chemical, biological and nuclear weapons was destroyed years before the Iraqi invasion.

The Boston Globe reported that Mr Kay, who was hired by the CIA in June to direct the search, had made the claim in a classified briefing to two Senate committees.

The newspaper quoted officials who had seen a summary of his report as saying that Republican Guard commanders had been ordered to launch chemical-filled shells at troops.

"They have found evidence that an order was given," a senior intelligence official said, adding there was no explanation of why the weapons were not used.