Diablo III's first (only?) expansion pack will be out on March 25.
The expansion pack itself gives you a new hero — the Paladin-y Crusader — a new act, and new features: an NPC artisan called the Mystic; a new mode in which you can ignore the story and start new games with every waypoint unlocked; and Nephalem Rifts — or loot runs — totally randomised dungeon crawls meant to emulate boss runs from Diablo II.
That "Digital Deluxe Edition" up there, by the way? Here's Blizzard explaining what that is:
You also have the option to prepurchase the Digital Deluxe Edition, which contains a wealth of in-game goodies: a collection of exclusive helm- and weapon-transmogrification recipes to distinguish your hero among the champions of Sanctuary; a loyal Spectral Hound minion to keep your adventurers company on their epic journeys; three additional character slots to accommodate new heroes; an in-game Treasure Goblin companion pet for World of Warcraft; and an assortment of Crusader-themed Battle.net portraits and Malthael-themed decals for StarCraft II.
Like Diablo III itself, Australians pay $54.95 for the standard version and $74.95 for the Digital Deluxe Edition. Compared to $39.99 and $59.99, respectively, for US prices. [Battle.net]