If you are a developer or Android super-fan who has signed up for the Google I/O 2016 lottery, then you might want to start checking your email for an invite. Google started shipping out the results to inboxes. If you haven't received one immediately, there's still hope. Google usually sends out the invites in separate groups, so you may just need to keep looking for it later this week.
The registration window for folks who receive an invite is 24 hours. It's possible that unused or declined tickets might make you a lucky winner later. Be sure to sound off here if you are one of the lucky folks who won an invite!