I asked my publisher if I could make some chapters of my forthcoming book freely available on line. After a month of deliberation they have come back with a 'no' from the rights department (but I could link to their contents page if I wanted - gee, thanks). I sighed with the inevitability of it. They just don't get it do they, publishers? On a purely capitalist note putting out a few chapters is a very effective marketing ploy. People will read a couple but are unlikely to find all they want and so, my guess, will be more likely to buy the book.
A slightly less direct effect is that releasing some chapters generates discussion around the ideas, which in itself creates the context for the book. Okay, my book is not exactly The Tipping Point or The Wisdom of Crowds, but within its readership this environmental massage is probably still worthwhile.
But the point is a bigger one - I understand publishers need to make money, but they haven't recognised the fundamental shift that has happened in value. It is no longer about what you keep protected that counts, but the extent to which you, are connected, linked to, commented upon, shared with. If you can't be connected to you don't exist.