If Amazon can sell a paperback book for 8$ and they are they are taking a hit at 10$ per ebook then clearly there is a mistake somewhere on the supply chain.
Maybe you're confusing a "hardcover ebook" with a "mass-market paperback ebook". :-)
But seriously, I found the answer in Stross's full blog post: "Right now, many of the largest publishers charge a cover price for ebooks that is 80% to 100% of the hardcover price." One would think that once a book goes from harcover to paperback the publisher would reduce the ebook price to match, allowing Amazon to sell ebooks marginally cheaper than paperbacks without losing money, but maybe they aren't doing that.
