Sort of off-topic, but I was talking with a novelist this morning. She was cooing over my iPad, undecided whether reading books on it was a good or bad idea. Something about the tactile experience of reading a physical book, and will they go the way of physical CDs? Anyway, she told me generally authors make a whole 25p (about 40 cents) per £10 novel sold. An author really needs to shift a LOT of novels to make any money at all (unless, I guess, you are a J K Rowling or Ian Rankin and can negotiate good rates AND sell lots).
I really hope that iBooks/Kindle and other digital distribution formats can actually mean a little more money for the writer, and not just the publisher, printers etc.
full disclosure: I'm a wannabe novelist.