Not to bump an old thread but does this only work with Amazon content? I finished two books this week from Baen and did the rate and share thing at the end but neither ended up on my Facebook or Twitter page.
I tried highlighting and sharing a passage in one of the books and got a message saying that this book doesn't support sharing. Both books were sideloaded with Calibre. Being Baen titles, Amazon doesn't sell them as eBooks so I'm guessing this is why it doesn't work?