If you thought that monthly subscriptions or Free2Play games were the only options to monetize a game, Blizzard has news for you: In Diablo III Blizzard will not sell you anything, but will take a cut from players selling each other virtual items for real money. The goal is to offer players the RMT they want, without enabling third parties to profit from it. By not selling things they can also believably claim that the game isn't designed around item sales.
Rob Pardo also said something about the release date of Diablo III: "We're working hard to get to this year, but it's going to be tough. So it either makes this year, or it falls into next year." Translated from company speak this means Diablo III is certain to come out next year.
Some people won't be happy to hear that Diablo III will only run when connected to the internet, even if you are playing the single-player game. I assume this is a necessity for a game with secure virtual items for real money trade: You do not want to have the information about the virtual items client side, where they can be manipulated. Duping gold in Diablo I was possible, but in Diablo III it would create major legal headaches.