Now if you search on your mobile device for a book, if there is an audio version of that book, let's say on Audible, Google will let you click on that as an option to get the book. Most recently, Google added libraries as an option to get the book but now they linked up with Audible to bring the book to you via audio.
This seems to only work on mobile, for example, here is Hillary Clinton's new book:
Notice the Audible option as well as a way to filter to see this book available as an "Audiobooks"?
Here is the screen shot from Google's post on Twitter:
Hmm, I have to drive to Boston next week, which is about 3-4 hours - maybe I should try some audiobooks?
Forum discussion at Twitter.