A little late with this Kryptos talk, but if you follow this link you can watch the 1 hour talk that Sanborn gave for Big Techday 6 hosted by TNG on the course of his work with some mentions of Kryptos, the CIA and the NSA.  I highly recommend it if nothing more than to show how much work he puts into his different projects and how one will often transition into another.

I enjoyed his sour grapes over Dan Brown as well.