Of the multitude of necessities that mankind remains stubborn and loyal to, the unknown seems to be the greatest inspiration of them, and our fascination with that which we do not know has the ability to overwhelm, taunting us with its mocking knowingness.
Slashdot today unshifted a story on the solving of the Cyrillic Projector Code, a sculpture by James Sanborn at the CIA HQ. more info here, including a pointer to Antipodes, what appears to effectively be the next puzzle on the list. Despite looking really good, I love the way these sculptures are yet another example of permanent, longstanding mysteries, just waiting to be solved.
Similarly, Kuro5hin carried a story about Fernando Pessoa recently, which I haven't read through yet, but he seemed to lead the public into a net of trickery and string to be untangled.
Puzzle setting has been an art since we learned how to think. Or thought to learn. There must be so much about us that we haven't figured out yet, whether it be man-made or not.