As this Joystiq post from yesterday decrees, the DaVinci Code puzzle quest has launched. It's now a module that you can load into your Google home page; just added it to mine.

"This movie tie-in game fits with the book's themes of brain-bending puzzles, and it should hopefully be an enjoyable ride, with puzzles being issued daily until May 10 -- coincidentally, the start of E3 -- and a prize draw for those who answer all 24 puzzles correctly."