With worldwide sales of more than 40 million copies, including 4 million in Britain, The Da Vinci Code and its blend of conspiracy theories, shadowy secret societies and thrilling adventure has already spawned an industry of its own.
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“Disguised on the jacket of The Da Vinci Code, numerous encrypted messages hint at the subject matter of Dan Brown’s next Robert Langdon novel.”

A faint grid reference written in reverse on the cover leads, with an adjustment of one degree, to a sculpture called Kryptos in the courtyard of the CIA’s headquarters in Langley, Virginia. Kryptos is covered in about 1,800 letters of code, much of which is still a mystery despite its location at the workplace of some of the world’s shrewdest cryptographers.

I wonder if the folks at the NSA cringe every time someone refers to the CIA as being the crypto agency. Or whether they see it a good "cover" for their own mission. ;)