Amazon (AMZN) will start to sell books on the Apple (AAPL) iPhone. It may not work well. There is still little evidence that consumers want to read books on electronic screens. The Amazon Kindle has sold reasonably well, but it is hardly a mainstream product yet.

According to The Wall Street Journal, "Amazon's software application, which can be downloaded free of charge, allows iPhone and iPod Touch users to read books or periodicals purchased on the Web or through their dedicated Kindle device, usually for $9.99."

The "electronic book" still has several drawbacks. One is the battery life of the reading devices. Another is the eye strain of reading books on relatively small screens. But the last and perhaps most powerful reason that these products may not sell is that a book is as portable as a Kindle, and it's easier to underline or tear out pages.

Douglas A. McIntyre is an editor at 24/7 Wall St.