Drupal usability study at Google
At time of writing, Google employee Becky "technika" Gessler is performing a Drupal usability study which is streaming LIVE for anyone to watch. But you can also watch previous sessions using that link. According to her announcing blog post, there will be 7 participants and each session will be one hour. The previous Drupal usability study was four years ago at the University of Baltimore. Those results were used in the D7UX project to improve the user experience in Drupal 7.