Amazon's Kindle app for the iPhone and iPod Touch has recently introduced a feature that highlights sections of a book and if you touch the highlighted text it would tell you how many others have also highlighted that part of the book.
I see tremendous value in this. I would love to 'share' sections I highlight with a selected group of people. Currently it just shows the count of all other users who also highlighted the same thing. You don't quite get the "social reading" aspect but you get an early sneak peak of where this is going.
Now this section in the photo above is, ironically enough, from a book called "Empire of Illusion: The End of Literacy and the Triumph of Spectacle" in America. A book that goes to great lengths to disparage the end of privacy and the triumph of exhibitionism and voyeurism that it basically equates to spectacle. It fundamentally wages war against TV, celebrity and the vapid culture of social media that promotes people to live their lives in public. I wonder what the author would think about his book being shared socially this way now and in the future.