BlizzCon 2011 kicked off this morning at the Anaheim Convention Centre in California, as president Mike Morhaime took to the stage to welcome 26,000 attendees to the annual celebration of all things Blizzard.

Speaking to the frequently raucous crowd this morning, Morhaime took time out to recognise two milestones reached in 2011 – Blizzard's 20th anniversary, and the 15th anniversary of the Diablo franchise. Morhaime also revealed that World of Warcraft subscribers will receive Diablo III free by utilising an "annual pass". Subscribers who sign up for this pass will be billed monthly, and have immediate access to Diablo III as soon as it's available.

In addition, Morhaime revealed the contents for the Diablo III collectors edition, which will feature in-game items for Diablo III, World of Warcraft and StarCraft II, an artbook, DVD, and a soulstone USB drive preloaded with Diablo II, which can be set in a holder shaped like Diablo's skull.

Following this announcement, Chris Metzen took to the stage to introduce the newest World of Warcraft expansion: Mists of Pandaria.

The Asian-inspired expansion is set in the new continent of Pandaria, and will see World of Warcraft's level cap raised to 90. Mists of Pandaria will also feature new dungeons, new PvP content and a new talent system, as well as the introduction of the Pandaren race, and the Monk class.

More information is expected to be revealed about this expansion over the next 48 hours.