In order to play Diablo III you will need to be online at all times, not only for authentication, 1UP reports today. The reason, according to Blizzard's Rob Pardo, is the Battle.net features the game will ship with - including a friends list, cross game chat, a banner that changes style depending on your achievements in the game and that your characters are stored on Blizzard's server.
Pardo acknowledges that some players will want to play the game offline, say on a laptop while flying or if your connection goes down for whatever reason. "I want to play Diablo 3 on my laptop in a plane, but, well, there are other games to play for times like that," he says.
1UP also reports that the in-game auction house for Diablo 3 will use both gold generated inside the game and real money - if you want to sell that epic sword of awesomeness you can do it and make a buck at the same time. Take a look at the run-down straight from the horse's mouth at 1UP and decide for yourself if that's something you think is a good idea or not.