Voynich Manuscript) it's now been cracked:
Now a team of Swedish and American linguists has applied statistics-based translation techniques to crack one of the most stubborn of codes: the Copiale Cipher, a hand-lettered 105-page manuscript that appears to date from the late 18th century. They described their work at a meeting of the Association for Computational Linguistics in Portland, Ore.Full story at the New York Times. Cosmic Log elaborates on the content:
Discovered in an academic archive in the former East Germany, the elaborately bound volume of gold and green brocade paper holds 75,000 characters, a perplexing mix of mysterious symbols and Roman letters. The name comes from one of only two non-coded inscriptions in the document.
Kevin Knight, a computer scientist at the Information Sciences Institute at the University of Southern California, collaborated with Beata Megyesi and Christiane Schaefer of Uppsala University in Sweden to decipher the first 16 pages. They turn out to be a detailed description of a ritual from a secret society that apparently had a fascination with eye surgery and ophthalmology.
The manuscript, available in several formats from Uppsala University's website, describes the procedure for initiating new members of the society. At one point, candidates are asked to read the writing on a blank piece of paper. When they can't, they're told to put on eyeglasses, and then they undergo an "operation" that involves plucking a hair from the eyebrow. After the operation, the blank paper is replaced by a document laying out "the entire teaching for the apprentices."