From the first page in "The Lost Symbol":
Fact: In 1991, a document was locked in the safe of the director of the CIA. The document is still there today. Its cryptic text includes references to an ancient portal and an unknown location underground. The document also contains the phrase "It's buried out there somewhere." ...
Heh, Brown's new book has multiple Kryptos references in it. The "Fact" part at the beginning is obviously referring to Sanborn's message, though Brown is twisting K2 and K3 together a bit. The "ancient portal" is actually King Tut's tomb in Egypt, not anything on the grounds of the CIA.
I'm also tickled that Brown included an encrypted reference to me in the book. He's done this in his other books, putting anagrammed names in for the characters. For example, in "The Da Vinci Code", the character "Leigh Teabing" is named after Richard Leigh and Michael Baigent (Teabing is an anagram of Baigent), the authors of "Holy Blood Holy Grail", a pseudoscience book that Brown used as source material for DVC.
So in the Lost Symbol, there's a CIA analyst who's looking at the Kryptos sculpture in chapter 127. The character's name is "Nola Kaye", which is an anagram for "Elonka"! Pretty cool, thanks Dan!
More info on Kryptos, see The Kryptos FAQ
Kryptos (and Elonka) mentioned in Dan Brown's new book "The Lost Symbol"