OK, so how to do this. Obviously we want to discuss a book, and so we'll chose one for a month say? Timings can be worked out as we go and we see how long it takes everyone to read along, and obviously will depend partly on the book.
So various ideas for how it could work...
Anyone can make a post as it goes along - obviously would have to cut to avoid spoilers so possible labelled as the chapter you're at so that people can decide whether to read or not.
Pros: makes sure everything you want to say gets discussed
Cons: Could lead to loads of posts which would be difficult to sort through for someone coming along a bit later.
Post at the end of each chapter/section. I make a post titled with the heading of each chapter (or likewise, however the book can be organised). We use the comments section to discuss it - threads etc. As well as these posts, we could have a 'suggestions box' for each book, if there was another point you wanted discussed it could be put in here, then an entry would be added for it.
Pros: Easy to sort, organise, means people can read at different speeds.
Cons: Could miss important bits out (though with suggestions, hopefully it wouldn't), and not sure quite how well the comments thing would work if a large number wanted to get involved.