Diablo 3 - Design Disassembled @ GameSpot

Design Disassembled is the title of a GameSpot article that covers a BlizzCon panel lead by a bunch of senior Blizzard developers:

The end result of this is a game that tries to tell a story in multiple ways, some more direct than others. For example, a level can tell a story based on its finer details whereas interacting with non-player characters during a dungeon sequence creates opportunities for smaller bits of story.

What's more interesting is the addition of optional story elements in the form of lore books, which players can choose to ignore completely or track down every single one, depending on what they want out of the story. When used, these lore books play an audio file narrated by the character they're associated with, but the key is that the player can still fight and do other things while it's playing.