If you want to read this basic Linux graphics driver development book, it's being housed in Git and can be seen from this Git repository. As can be seen from the log, the recent activity to it was pushed just 11 days ago.
This book was originally started by Stephane Marchesin from the Nouveau project who is now working at Google on Chrome OS.
But before getting too excited about the book, at this week's X.Org Foundation board meeting (the IRC log), the book sprint was mentioned "kind of fail." This graphics driver book sprint was kind of a failure because as Bart Massey says, "having a bunch of pre-written stuff but not the author made it really hard to work on... I think that if we try again next year, we need more people and better advance planning. In particular more people, [especially] more people knowledgeable about whatever we're going to write about."