Jay Wilson, lead designer for Diablo III, provided fans with a lengthy update on the status of the “player versus player” combat mechanic that Blizzard has been promising since before the game was released. In short, team based combat has been dropped from their plans but one on one dueling will be added to the game with patch 1.07, which is still a ways away.

I personally think it would be better to implement it with the release of the expansion – but that would definitely make a lot of people who paid for the original game expecting PvP angry.