Here's the thing about social reading and social media: social reading is about discussing ideas, while social media is about broadcasting ideas. Unfortunately the two do not mix very well in the implementation that I've seen (Kobo):

• "Interaction" with people who you know (e.g. on social media sites like Facebook) tends to be uni-directional. The only way to discuss anything is to go to their website.
• Discussions tend to be with people who I don't know (e.g. people who bought a particular version of a particular book from a particular store).

P.S. HarryT, I understand your point on advertising, but it is also making it hard to comment on this company's product.