This book is pretty well known in the HN space, are you referring to "The Site Reliability Workbook"? That looks like it hasn't even been released yet in print, which is very cool that they are offering free downloads.
If so, thanks for the link! Can't wait to pour through this bad boy.
Seems like the title got changed as usual for something generic and meaningless. I think the news here is that Google released a new "Site Reliability Workbook", downloadable for free for a month.
For anyone else who missed it, scroll down on the page to see the workbook. The first time I checked I only saw the SRE book, which has been available online for several months.