The International Publishers Association released a document on how the day is celebrated around the world.
Since 1995, the 23rd of April (birth date of Shakespeare and Cervantes) has been designated by UNESCO as World Book & Copyright Day, with many events taking place to celebrate books, authors and reading.
In Madrid, the Premio Cervantes, the most prestigious literary prize in the Spanish language, will be awarded by the King of Spain to Elena Poniatowska, a Mexican writer and journalist. In Budapest, the International Book Fair will open. In the United States, volunteers will distribute 500,000 books provided free by publishers, with one third going to school pupils. In many other countries, World Book Day events take place on March 6th.
You can read about the different traditions and events associated with World Book Day in a specially commissioned IPA report, available here as a pdf.
It's also World Book Night USA! I'm giving away copies of Jamie Ford's Hotel on the Corner of Bitter and Sweet at my Brooklyn subway plaza. Any other givers out there? Chime in!