I received the following email from Kare Anderson. I wonder if Readium might not be useful here:
I work as Leader, Collaborative Strategies for Deloitte’s Center for the Edge, a research group led by John Seely Brown and John Hagel. We are exploring the possibility of creating some short ebooks that would be “social” – that is enable readers to share comments in the book. I have seen a bit about the Sophie Project, Monocle and understand Kindle enables friends’ comments. Have you come across any organization creating a shareable format?