The notebook (pictured left) was just handed out in advance of the event's opening ceremony, and was promptly captured by worldofwar.net. The show's banner image also features Diablo lording over StarCraft II's Kerrigan and Wrath of the Lich King's Arthas.
New Blizzard game announcements have been known to be revealed in the corresponding event's literature, as was the case with World of Warcraft: Wrath of the Lich King's announcement at last year's Blizzcon.
Diablo III was strongly rumored to be the announced project at Blizzard's WWI for weeks. A splash image on Blizzard.com has slowly revealed a face that resembles the title villain, with five runes surrounding it in a famililar pentagram formation.
Any details of the presumed Diablo title--including whether it will shift to the MMO genre--are still unknown. The opening ceremony is set to be held at 11:45am Paris time (5:45am EST). Stay tuned for further updates to this story as things get underway.