Diablo III | PvP gameplay Blizzcon 2010

just in from Blizzcon 2010 - Player vs. Player combat
from the press release
vP (short for 'player versus player' combat) has had a storied history in the Diablo series. For Diablo III, we've decided to take it in a new direction to ensure that it's deep, organized, frantic, and fun.
Diablo III's PvP battles are fought in arenas spread out across the world of Sanctuary. These arenas aren't random -- they're all unique, designed with differing amounts of terrain and cover. You participate in PvP using the character of your choice, with access to all of the gear and skills you've accumulated playing the game in single-player or cooperative mode.
You'll learn many of the fundamentals of PvP (like how to avoid attacks or target specific foes) by playing the single-player game, but PvP differs in that it isn't an ideal venue for gathering new weapons and armor. Your rewards for shedding blood in the arena are purer than that: bragging rights, the joy of sending friends old and new to their swift and inglorious deaths, and points that represent how far you've progressed on the path to fame and glory.
When you participate in ranked games (fights that pit two opposing teams of players against each other in 'best of' matches), you'll earn points for advancement based on kills, accomplished objectives, wins, and other factors. Points lead to multiplayer achievements, titles, and more. Our system is focused on encouraging furious combat and multiplayer progression, not stringent competitive rankings, so you'll earn points after every match and Battle.net matchmaking will pit you against similarly skilled opponents.
We're also looking into other PvP game types that exist outside the ranking system, like 1-on-1 duels and mutually chosen team battles (for example, you and your friends could divide into two teams for an arena showdown). We'll have more information on the availability of these game types in the future.
Our aim for Diablo III's PvP is to set you up with dangerous, exciting gladiatorial matches, let you battle it out with other players at your own pace, and allow you to proudly display your rewards. We've added a robust system to remove the obstructions that may have kept you out of the action, so that you can focus on what really matters: answering the age-old question of 'who would win in a fight' -- with a gauntlet to the face.