One way to look at this might be that North Korea wants to get off the Axis list, and is making a pre-emptive disclosure, to pave they way for negotiations.
They can see what is or is about to happen to "rogue" state Iraq. Self preservation may be the motivator.
Now one can see that the "Axis of terror" had a good foundation--we must have known quite a bit about this revelation.
What is China's role? Probably not a small one.
Just posted the same idea on another thread. They want to get out of the bullseye. There was a thread some weeks ago that said quiet was progress being made behind the scenes there. Why else would they volunteer this information if not to pre-empt Bush when their turn comes?
I say the Bushies knew this "surprise" announcement was coming and it is all part of a larger plan. The media is reading this all wrong as usual.