Learning from the experience, Blizzard announced early on that the next batch of 3,000 tickets would be sold via lottery, giving everyone a fair chance at attending the event. There are quite a few limitations, such as having an active Blizzard Account that was created on or before August 12, when the first batch of tickets sold out. Note that a Blizzard Account isn't the same as your World of Warcraft account or an account for other Blizzard games. It's an account made specifically for their online store, so wannabe attendees who haven't created an account are flat out of luck.
Also out of luck are residents of countries that aren't the United States, Canada, Australia, New Zealand, Singapore, France, the United Kingdom, Germany, Austria, Denmark, the Netherlands, or South Korea. So yeah, all you Blizzard fans in Zimbabwe, I'm looking at you. Alright, the Philippines isn't on that list, either, so we're all on the same unwelcome boat. Just like the Wrath Beta, Blizzard will hold an opt-in period for Blizzard Account holders and will pick 1,500 lucky chumps from those who opted in, allowing the purchase of up to 2 tickets each. Learn more about the details on the BlizzCon lottery through their BlizzCon FAQ.