The PAX registration system went live on April 25, it crashed within fifteen minutes. The servers went down, Penny Arcade switched registration vendors, and the servers were brought back up on the morning of May 2.
Later that day, Penny Arcade updated their site with the following message:
"We're shocked to be writing this... but we're completely out of 3-Day badges for PAX Prime 2012. There are still single day passes, and while it's impossible to say how long they will last, it is fair to say "not very long."
But to be perfectly clear: Three-Day passes are gone for good, and the only way to attend PAX is to grab the single day passes that are still available."
Last year it took over 20 days for PAX Prime to sell out of 3-day passes. This year, they sold out in less than 24 hours, including the small amount of time servers were up on April 25. The likelihood of 1-day passes selling out soon is very high.
PAX Prime has added a hotel registration system for attendees. Rather than having to search for individual hotels and comparing rates through a spreadsheet, the new system does all of that for you. This also includes potential savings for exhibitors and groups that reserve two or more rooms.
Congratulations to those who were able to pick up passes before they sold out. Good luck to those who are trying to pick up 1-day passes, or will try their hand at Craigslist or Ebay second-hand tickets. Myself, I might have to try for a media-pass, after I figure out which friends were able to pick up a ticket yesterday.
Update: As @Vapid Soul mentions in the comments, Friday and Saturday daily passes are now sold out as well. Expect Sunday passes to be gone before the day is out.
Update 2: Completely sold out. Scalped tickets are already selling on Ebay for over $200.