Dhruin
SasqWatch
MMOGameSite (catchy name) has a "Product Slate" that supposedly shows Blizzard's release schedule, including Diablo III for Q4 next year (and addons for 2013 and 2014) . It's completely unsubstantiated and comes from "a gamer, speaking on condition of anonymity", so take it as you will.
More information.
More information.