https://developers.google.com/events/io/help#reg_ions "I/ONs have attended at least five of the following as a paid attendee: Google I/O 2008, 2009, 2010, 2011, 2012 and the 2007 Google Developer Day in Mountain View. I/ONs receive a limited time opportunity to purchase a ticket during pre-sale registration. Eligibility as an I/ON is at Google's discretion."