UPDATE: Sold out in under two hours!
WWDC 2012 just announced and tickets are on sale at https://developer.apple.com/wwdc/
Two years ago, at $1600/ticket plus expenses, I wasn't sure if I would go, and tickets sold out in 8 days. Last year I determined ahead of time that I would go, and tickets sold out in one day! But I did indeed make it and got to see Steve Jobs one last time. Expect tickets to sell out today, so don't delay!