MJD: I hope people will buy copies of the book to keep. MKP is nervous that having the book on the web site will hurt sales. I don't think it will, but I'd sure hate to be wrong.
I don't of course know how it will work. Partly because it's more convenient and meaningful to have a physical book, partly because I subscribed to the list and want to support it, I have ordered a copy and will be enthusiastically reading it once amazon.co.uk actually get hold of it. I wonder if this is because of the community aspects of Perl. For example, if a mass market book/album/film I wanted were freely and legally available online, would I download it for free, while paying for HOP because I want to support my club?