With the popularity of the book 'The Da Vinci Code,' the magnitude of this event is much greater than it would normally have been. This is a big event. I guess it would be pointless to give a bio on Leonardo Da Vinci here now, or to try to give a background on 'The Da Vinci Code.' I will suggest getting your hands on the recent biography on Da Vinci from the A&E webstore. It's outstanding, and gives a great look into Da Vinci, and that time period. Any list of the greatest men of all time will feature the Tuscan Leonardo Da Vinci.
Lastly, here's a list of related links: Da Vinci in Wikipedia (with a large number of related links at the bottom), Da Vinci: An Exhibition of Genius (offical website), and the companion Da Vinci webstore. Big Da Vinci exhibit in San Francisco, ya can't miss it!