The Demon Hunter will be the fifth and final class in Diablo III. Also, WoW players will be able to download Cataclysm in advance to play on launch day.

UPDATE: Blizzard just updated the Diablo III site with more information on the Demon Hunter, as well as details on the PvP system.

The BlizzCon 2010 Opening Ceremony just ended, and the biggest announcements were for Diablo III fans. Senior VP of Creative Development Chris Metzen unveiled the Demon Hunter as the fifth and final class and announced that PvP battle arenas will be a part of the game. There's still no word on a release date, so we'll just have to wait and see when Diablo III will actually hit the shelves.

As far as World of Wacraft is concerned, President and CEO Mike Morhaime announced that players will soon be able to pre-order Cataclysm directly through Blizzard and download the expansion in advance of the launch. Cataclysm is set to go live on Dec. 7 at midnight PST, and Morhaime said that players who download Cataclysm will be able to jump right in and play at that time. Of course, we all know to expect downtime and server issues on launch day.

In other WoW news, a Moonkin Hatchling charity pet will go on sale in November. Morhaime also mentioned that Blizzard will be auctioning off server hardware that was used to run specific realms in World of Wacraft. All of the net proceeds from the auction will be donated to charity.

Blizzard has designed four all-new custom StarCraft II maps: StarJeweled, Aiur Chef, Left 2 Die and DOTA. They will all be released for free via Battle.net in the future, and BlizzCon attendees will be the first to try them out.

The majority of the ceremony featured Metzen talking about the power of geekdom. He showed slides featuring cultural icons such as Star Wars, Batman, and even EverQuest. "The truest spirit of BlizzCon is you," he told the audience. "This is about our collective geekiness and how it brings us all together."

Be sure to keep an eye on Wowhead's live BlizzCon blog to get more news from the convention throughout the weekend! Diablo III fans will definitely want to check out the panel on the Demon Hunter class.

- Darryl Gangloff, editor-in-chief