According to Google, there were exactly 129,864,880 books in the world on August 5, 2010.
Google collects metadata from many providers (more than 150 and counting) that include libraries, WorldCat, national union catalogs and commercial providers.
There are close to a billion unique raw records which are analyzed to reduce the level of duplication within each provider, bringing the total down to close to 600 million records.
Twice a week Google groups all those records into “tome” clusters, taking into account nearly all attributes of each record to remove duplicates.
Counting only things that are printed and bound, they arrive at about 146 million. Removing serials results in a total number of books: 129,864,880 ... on August 5, 2010...