"Beginning on April 17th you will embark on a quest that requires skill, intellect, and perseverance. For 24 days, you will encounter unique challenges. These daily puzzles will pull you deeper into the world of The Da Vinci Code. Answer all 24 puzzles correctly for a chance to win untold riches."There's a bunch of prizes to be won: "You could win trips for four to New York, Paris, Rome, and London, a colossal Sony Electronics package, and more."
Update: Looks like everyone's looking online for the solutions now, but the first day's puzzles had many different answers so it'll be interesting to see if each day there are many puzzle variations.
Update 2: This blog has solutions to each day's puzzle.