USA Today.com also picked up the AP story.
I find myself in the unenviable position of agreeing with SATTSO. Based on the limited amount of info in these stories, I think this is probably a case of a soldier trying to take home a little souvenir of his service in the form of explosive materials, and being too dumb to know that the checkpoint would probably discover them.
Of course, I feel obligated to point out that the AIT didn't discover the explosives, nor did an invasive rubdown, nor did even the ETD swabs (which I support as a primary search methodology) - it was initially detected by the carry-on x-ray scanner and subsequently identified by visual inspection. This part of the system, it seems, not only works exactly the way it's supposed to, but also seems to have done the job that $1.4 billion worth of AIT is supposed to do (and thus far hasn't).
Fortunately, this guy probably posed no threat to the aircraft and was simply trying to smuggle something prohibited home with him. It is possible that the guy truly did intend to blow something up and simply hadn't attached the detonating equipment to the explosives yet. It's also possible that he wasn't carrying explosives at all, but was carrying something else wrapped in used explosives wrappers. However, nothing is conclusive as yet, so I'll withhold judgment on whether this a Good Catch or the first truly Big Catch.
No matter what actually happened, I think the guy was obviously an idiot, because trying to bring explosives wrappers onto a plane with him, no matter what was inside the wrappers and no matter what he intended to do with the wrappers and their contents, was just plain, old-fashioned stupidity.
This is one of the few incidents where TSA seems to have done their job correctly.
That's one. Only about 700,999,999 to go for 2012 to be a banner year for TSA.