I've been digging into the evidence (and lack thereof) and reached the following conclusions, arranged in time-line order. None of them require noting the suspicious timing of the report after so many months, the threatened status of El Baradei as he seeks a new term as IAEA head over US objections, or any partisan inclinations on the part of the media outlets involved.
The U.S. asked the IAEA to destroy the stockpiles in 1995. The IAEA refused, citing the explosives as legitimate "dual-use" material. The material was present only because the IAEA under El Baradei refused to destroy it.
In December, 2002 the IAEA found that 35 tons of HMX was missing. The Iraqis claimed that it had been used for legitimate construction purposes. The IAEA began another inventory.
The stockpiles of explosives were last seen in early January, 2003, when the IAEA inventoried them and placed seals on the bunkers they were stored in.
In early March 2003 IAEA inspectors visited Al QaQaa and found the seals intact on the HMX bunkers (holding 192 tons at time of sealing). They were not permitted to check the RDX and PETEN bunkers, and this was noted in their report. NOTE: It is certainly possible for the Iraqis to fake seals in any case. The explosives were NOT "seen" in March. The seals on one set of bunkers were, and other bunkers were not seen at all because of Iraqi interference.
April 3, 2003--the 3rd ID comes through Al QaQaa. Reports differ--by some accounts they had a list of items to look for, and once CENCOMM was notified the items were not where they were supposed to be the 3ID was told to move on. Other accounts say they did not have a list. All accounts agree that they found a cache of "thousands of boxes" measuring 2 inches by 5 inches that contained "three vials of white powder" and chem/bio weapon instructions. The powder was tested and found to be explosives, and it is highly likely that this was HMX or RDX. By all accounts the complex had suffered air strike damage, many buildings were completely destroyed including two large bunkers, and many others severely damaged. There were large quantities of conventional munitions ("AK 47's, ammunition, and artillery shells") to be seen in some of the damaged and collapsed buildings. No reports that any IAEA seals were seen. By some accounts the vials found were destroyed, other accounts do not mention this.
(NOTE: If the "thousands of boxes" were RDX or HMX, it is worth noting that the full amount of 380 tons would have been many millions of boxes. This was not formed explosives, but raw material in a lightweight powder form. More on this later.)
April 10, 2003--the 2nd Brigade of the 101st Airborne, with an NBC embed team along, stops in Al QaQaa for a 24-hour breather. They secure the area and rest. They do not have orders to search for the explosives. Some of the troopers check out the area--naturally, as securing the area requires some inspection. One of them (Ken Stillman) reports seeing two large empty bunkers with obvious signs of heavy traffic--lots of boot prints (not ours) and truck tracks. No signs of either the IAEA seals or explosives are reported.
On either May 7 or May 27 (I saw five accounts, with conflicting dates) the 75th Expeditionary Task Force (75ETF) arrives at Al QaQaa to "I & D"--inventory and destroy. The explosives are not there, and the already-damaged site shows signs of extensive looting. The 75ETF destroys piles of munitions and leaves.
Last date confirmed as actually present: January 2003. Date on which IAEA inspectors were NOT allowed to check all seals: Early March 2003. Dates on which US Troops visited and did not find any IAEA seals at all: April 3 and April 10. Date known for a fact to not be present: May 27, 2003.
A few more points. This is not some super-explosive, but raw material capable of making into plastic explosive roughly 20% to 50% more powerful than TNT by weight. It was not even in usable form, it was a fluffy plastic powder that required fillers, binders, and stabilizers to make usable explosives. When reconstituted, what you would have would be either Semtex or C4, depending on the binders and formulation, and you would still require detonators. All of those are already widely available in the Middle East. Artillery shells and other ordanance, already scattered over Iraq in the hundreds of thousands of tons, contains these materials in their usable form, and has the advantage of having the appropriate matching detonators already in place.
Damage to the two large destroyed bunkers (described by members of the 3ID and 101st as "craters with rubble centers") is consistent with impact detonation of large amounts of raw explosives. Could some have gotten out after we got there, and then left again? Sure, but unlikely. The fact that the boxes that were found were labelled as bio-weapons suggests they were intentionally placed as "scare tactics." The condition of the destroyed bunkers is inconclusive, but they could have had some quantity in them that got wiped in air strikes.
Odds that the material was moved out of the complex before Coalition troops arrived, during the period when Saddam was scattering his munitions all over the countryside, even sending convoys over the border into Syria--considerably good. Odds that part was dispersed by Saddam and that most of the rest went ka-boom in the air strikes, with little left to loot--also good. Odds that millions of boxes of fluffy white powder packed in vials could be moved out through the Coalition lines in bulk after US troops reached the area, all of them on high alert for anything that remotely resembled chem/bio weapons, without one single box being intercepted, and concealed so well that NONE of it has shown up since--just about zilch.
Just my take from an actual review of known accounts. Your mileage may vary.