TECHNICALLY, loaning a book to a friend could be argued to be an act of piracy (as I understand it). You have not been given the right to distribute the book, and the company could be losing profit, as your friend wouldn't have to buy the book to read it. However, no publisher in the world would even THINK about trying to stop the "illegal" practice of book-loaning, even if they were to regard it as such. Much like spriting and sprite-comicing, using a PDF copy of a bok you own probably falls under the "You could argue that it is illegal, but nobody really cares." If they were to go after you (Instead of the people on Kazaa who distribute the stuff) they would need to give a warning first, so you would have your answer then, and not have any legal problems. I say, go for it.
Would the open gaming licence cover part of this?