We believe (though aren't sure) that they'll be selling more than 15,000 tickets this year, since that's what they sold last year and they're using even more of the convention space. If that's true, then Blizzard probably went through only about half of the tickets, and will sell the rest during the second session on the 30th. But that's probably not much of a consolation -- given the frenzy around this last Saturday, there'll probably be more people trying for tickets, and given the prices on eBay, possibly more scalpers clogging up the queue. We'll see.
Update: Lots of people point out, rightly so, that I missed something in my guesstimates of how many tickets were sold: you could purchase up to five. My personal guess is that the majority of people bought only one or two, but even if you go with three as the average, 5,000-8,000 people in the queue is actually 15,000-24,000 tickets. Blizzard probably did sell the majority of tickets on Saturday then, not just half. So the process on May 30th will presumably go even faster.
BlizzCon 2009 is coming up on August 21st and 22nd! We've got all the latest news and information. At BlizzCon you can play the latest games, meet your guildmates, and ask the developers your questions. Plus, there's some great looking costumes.