I'm not trying to become a spokesperson for the Kindle, but it does change the reading experience.
One of the Kindle's features is that it allows you to highlight text or add notes to it. You can also share your highlighted text on Facebook or Twitter. (Edited to add: the book is automatically cited.) And if you're reading a book that other people have shared highlights from, you can see those as well. (You can turn public highlights off if they distract you.) What I like about the public highlights is that they make me feel like part of a community reading a book.
(I don't interact with a lot of SF readers in my daily life, and I don't belong to any SF book clubs. There are probably forums out there where I could discuss my reading, but as a writer, I'm not comfortable posting about other writers' books. If I say anything negative, it could come back to haunt me.)
I also like sharing my highlights on Facebook. I'm currently rereading my beloved Zen and the Art of Motorcycle Maintenance by Robert M. Pirsig on Kindle, so if you're friends with me on Facebook, expect to see a lot of passages from that book popping up on my profile over the next few days.
Do you mark up your paper books? I generally don't, but ZMM is the exception for me. Do you like the idea of sharing your favorite passages with others? If so, would you do it for fun or publicity?