Registration is now open! Gogogogo!
Update 1: Academic tickets (for students) are now sold out.
Update 2: Looks like it's completely sold out now. That's a new record - 25 minutes (ish). Congrats to all who got a ticket!
Update 3: Vic Gundotra hit up G+ to let users who didn't get registered in time know that they won't be missing out on all the fun. We can expect all key sessions and the keynote to be streamed live, available for viewing after 24 hours, and Google I/O Extended viewing parties will be happening all over the world.