"There's probably the same or similar primary means of communication between the individual cells and their contact. There's no way that the guys planning on the building attacks are part of the same cell(s) that are assigned to creating radioactive slag."
IIRC, way back when, the KGB published a sort of spy manual in hard copy that extolled how they handled agents on US territory: How to spot tails, surveil safehouses, lose multiple tails and communicate in a clandestine manner. Might it be possible that AQ is using some of those techniques?
If they exist, the nuke cells have got to be the biggest operation since we managed to keep the Manhattan Project a secret. It can be done, but these guys won't risk any sort of exposure on any level. Their contacts will be face to face only in an area extremely difficult to surveil with any sort of electronic device or via direct observation.
After 911 I had a vision of OBL on a hilltop, his hands were cupped together. He bent his knees and spun around and put up his hands and released a butterfly. In the Koran it talks of the butterfly and cocoons and keeping them together by a sil thread. I didn't know this until I looked it on the net after seeing that vision.