CIA Kryptos Sculpture Has a Typo

It's not really a typo but an intentionally left-out X separator for
aesthetics on the sculpture that was intended to result in gibberish
when decrypted that would clue in the decryptors to reinsert a separator
and try again, except it ended up spelling something intelligible
instead of garbage so they thought they had decrypted it properly!

For nearly 16 years, puzzle enthusiasts have labored to decipher an 865-character coded message stenciled into a sculpture on the grounds of the Central Intelligence Agency's headquarters in Langley, Va. This week, the sculptor gave them an unsettling but hopeful surprise: part of the message they thought they had deciphered years ago actually says something else.