O'Reilly talks about the lessons learned by its foray into e-book publishing.

Many people, both inside and outside of the publishing and media industry, are skeptical about the potential of paid content on mobile phones, especially given the troubled history of e-books. I beg to differ. In December 2008, O'Reilly's "iPhone: The Missing Manual" was published as an iPhone app. Since its release, the app has outsold the printed book, which is a best seller in its own right. We're learning a lot from the experience. Here our some of the questions that we're starting to answer.

Was the iPhone app for the "Missing Manual" an anomaly? After all, iPhone owners are the most likely audience for the "Manual."

O'Reilly: Conventional wisdom suggests that when choosing pilot projects, you pick ones with a high likelihood of success. This was a best-selling author on a red-hot topic. We're gearing up to release about 20 more books as iPhone apps, but realistically we don't expect any of those to sell as well as this first one.

Is the iPhone the most convenient place to get content about problems you're trying to solve on a computer?

For many of our readers, a first or second pass through one of our programming books is mainly about orienting to the landscape and getting a sense of the platform and what's possible, not about solving a particular problem at hand. The iPhone is a perfectly suitable environment for that kind of reading.

Won't you make less money selling iPhone apps than books? The computer book market is the computer book market, period. It has a certain size, and that's it. If you convert that market into iPhone app buyers instead of book buyers, say good-bye to your publishing business.

It would be economically bad news to sell a $5 product to someone who would otherwise pay $50. But it's good to sell a $5 product to someone who would not otherwise be a customer (provided, of course, that the marginal revenue exceeds marginal cost). For Safari Books Online, for direct sales of our e-books and now for this (single) iPhone app, the data suggests that they have created growth without sacrificing print market share. For example, our market share for printed computer books sold at retail was 14% in 2004, and is now 16%. According to Nielsen Bookscan data, the print version of iPhone: The Missing Manual has sold nearly as many copies as the next two competing titles combined in the time period since the app version went on sale in December.

This data only goes back to mid-January, but the 90-, 30- and seven-day averages on Amazon sales rank for the printed book have been steadily improving, suggesting that sales of the iPhone app version are not cannibalizing print sales--and may even be helping them.

Apple says it is expanding iPhone features

Apple Inc. is broadening the ways that third-party software programmers can sell content on the iPhone.

Apple (nasdaq: AAPL - news - people ) says software developers now will be able to create applications that have items for sale within them, such as electronic books or additional levels of a video game.

he company unveiled the new tools along with the third generation of software for its iPhone during an event for journalists at its headquarters in Cupertino.

Apple launched the most recent iPhone last summer. The company sold 13.7 million iPhones in 2008.

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When the Kindle e-reader first appeared 14 months ago, Amazon-watchers were surprised to see the e-commerce giant redefine itself as a gadget maker. But Tuesday, when Amazon.com released a free application for the iPod and iPhone that allows users to read its e-books on those devices, it cemented its original book-selling mission.

In other words, it's all about the content.

The Kindle software for the iPhone and iPod, which Amazon.com (nasdaq: AMZN - news - people ) Chief Executive Jeff Bezos first hinted at during the release of the Kindle 2 last month, allows users to buy and read any of Amazon 230,000 e-books on any of the three devices and seamlessly move them among the gadgets.

While the software gives up the Kindle's exclusive hold on Amazon's digital catalog, it taps into a potentially much larger audience for Amazon's e-books--Apple (nasdaq: AAPL - news - people ) has sold around 15 million iPhones, while Amazon had sold only around 500,000 Kindles at last count, according to an estimate by Citigroup analyst Mark Mahaney. And that, says Forrester Research analyst James McQuivey, means Amazon has definitively focused on selling e-books above selling e-readers.

"This puts a stake in the ground around the idea that they really want you to be able to access the content you buy from them on any platform. And that's something we haven't seen other major media initiatives do," McQuivey says.

Apple's iTunes store, by contrast, has traditionally sold content tied to its music players--a bid to sell more hardware rather than content. Amazon, McQuivey says, has now made clear it's taking the opposite approach. "Amazon is saying, 'This is about books. We want you to feel that you can read our books anywhere, and we want you to buy more of them,'" McQuivey says. "They're saying, 'We're not a Kindle maker. We're a content provider and a content liberator.'"

Amazon may be liberating its content, but it's not liberating its hardware. Even as the company's book-selling platform expands, it's not likely to become compatible with other content providers. That could give the e-retailer a stranglehold on the budding market for e-books, a strategy likely to rankle publishers.

In an essay for Forbes last month, tech publisher Tim O'Reilly criticized Amazon's decision to close the Kindle to non-Amazon content (see "Why Kindle Should Be An Open Book"). Unless the company opened the Kindle to formats like epub, which work across a variety of non-Amazon-sanctioned devices, the Kindle would become irrelevant in two or three years, he predicts.