1:28 p.m. EDT: Sold out until May 30th. I'd really love to know how many tickets they released. We had people on staff in position 5000 in the queue not get a ticket.
Older updates after the break.

1:18 p.m. EDT: Queue is now over 21,000. 43% of the tickets are left for today.
1:12 p.m. EDT: Half the tickets are gone for today. Good luck to the ~20,000 of you in the queue!
1:10 p.m. EDT: Queue is now over 17,000. People are getting tickets, however.
1:09 p.m. EDT: It appears that the ticket queue is based on cookies, so if you leave it and rejoin you'll end up back in your original position. Do not try this though unless you're insane.
1:02 p.m. EDT: Queue is now over 12,000.
1:00 p.m. EDT: Tickets are on sale. Matticus is in position 840 after placing an order seconds after the order site allowed him to.
12:47 p.m. EDT: DirecTV and Web Streaming are not purchasable at this time. Nethaera posted as much in the forums a bit ago.
12:42 p.m. EDT: BlizzCon Store ticket page is located at http://www.blizzard.com/store/blizzcon09-tickets.xml
12:30 p.m. EDT: Half hour until BlizzCon tickets go on sale. Blizzard has taken down the armory to lighten server load, so it appears they're being proactive about things. This is good!
We'll post any news we get on the ticket selling here, including communication from blues via the forums or through other mediums. You can always find this post via the big banner at the top of WoW Insider that says "Click here for the latest ticket status."