Insight Editions will launch the Diablo III: Book of Cain (Hardcover) on November 15, 2011.
"This book is designed as an “in-world” artifact from the Diablo universe, Diablo III: Book of Cain includes Cain’s revealing meditations, as well as dozens of sketches and color artworks depicting the angelic and demonic beings who wage constant war with one another.
The last Diablo product containing lore was published in 2007. After a four-year hiatus, this Diablo III product might hint a Q4 2011 release date of Diablo III.
Several novels based on StarCraft II and the World of Warcraft expansions have shared a nigh simultaneous release date, some with a margin of a month earlier than the game."