Courtesy Wizards of the Coast

On Worldwide Dungeons & Dragons Game Day, games stores all over the globe host 4th Edition Dungeons & Dragons sessions.

"Worldwide" really means the United States, Europe and the United Kingdom. There are now multiple Game Days. According to Chris Tulach, RPGA Content Designer at Wizards of the Coast:

Last year, we decided to add a "launch party" element to Worldwide D&D Game Day, holding it on the weekend of the release of the 4th Edition core rulebooks. We had record numbers of people come out to give the new game a try (a first for many of them). A Game Day on a major rulebook's release weekend was a natural fit for the event, and organizers asked us to hold these events more often.

Players get a pre-generated character sheet and a miniature of the character they played. Dungeon Masters get the real prize: the adventure played that Game Day, a poster map of the encounter areas, and a pack of monster miniatures used in the adventure.

The 2009 D&D Game Days are run through the Wizards Play Network. If you're interested in running a Game Day, you must be a WPN Organizer.