The big change this time out for the dungeon crawler will be online co-op. Runic Games notes that the game will feature a free peer-to-peer matchmaking service to "meet new players of a similar level and interest." And this time around, the world will include "expansive" randomized outdoor environments -- don't worry, the dungeons are still there -- along with "random instanced and persistent dungeons." Expect new monsters, weather effects, a new story and LOOT!
Torchlight 2 will be playable at GamesCom later this month in Germany and at PAX Prime (Seattle) in September. The game will "initially" launch as a downloadable title in Spring 2011.
Update: Torchlight 2's initial launch will be on PC, with the Mac version rolling in at a "TBD" date. As for consoles, a Runic representative tells Joystiq, "We would love to bring both games to console, but we have no plans for it at this time."