I don't really think this is relevant to LessWrong per se, but I'm wondering if any smart folks here have attempted to solve this "internet mystery":
The internet mystery that has the world baffled: For the past two years, a mysterious online organisation has been setting the world's finest code-breakers a series of seemingly unsolveable problems. But to what end? Welcome to the world of Cicada 3301
Pattern-matches to marketing campaign. Though an unusually long-lived one if so.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.