According to multiple sources including USA Today, MIT professor Michael Hawley is the inagural holder of a new Guinness Record, for "largest published book".
His Bhutan: A Visual Odyssey Across the Kingdom measures 5'x7', weighs 133 lbs. and runs 112 pages.
It costs about $2,000 to produce, and he will sell copies for $10,000. The balance goes to a charity for the people of Bhutan. Books in Print doesn't have the real thing, but it does show a record for a compact version that retails for $100.