Defense Tech, a great military technology blog, offers another explanation for the decreasingly imminent North Korean missile test.
It seems that the Taepodong II missile uses a highly corrosive fuel - 20% gasoline and 80% kerosene. The oxidizer even has nitric acid in it, so it's not like you can fuel the missile and go about your business on a casual schedule. Defense Tech's sources say that the missile would need to be launched in the first two or three days, or the missile will basically ruin itself sitting on the pad.
Given that it is now day four since the ostensible completion of fueling over the weekend, it's starting to look unlikely that a missile is actually readied for launch. Is this another screw-up by the intelligence community, an attempt at militaristic diversion by the Bush Administration, or the Norks playing us for chumps? Interesting, in any case.