Originally designed to compete with tablet PCs, Apple's iPad contains the iBooks app that now competes for marketshare with the Kindle and the Nook. The gauntlet was thrown down when Apple offered 70 percent of revenue from the sales of these books to publishers, the same arrangement afforded developers on Apple's App Store. Others have since matched Apple's deal with publishers.
DRM
The DRM experience on an iPad is much like their music service, iTunes. Depending on the book and/or publisher, some books come with DRM and some don't. Unlike iTunes, you don't have to pay a premium for this privilege to access content without DRM, but some books are unavailable without the copyright protection. Like iTunes, books from the iBookstore are limited to five computers you've authorized and infinitely downloadable to any iDevice you own.
However, iBooks does support reading PDF files and the ubiquitous (and DRM-free!) ePub format. With these additions, Apple boasts 30,000+ free books this way, mostly from Project Gutenberg. No other e-book formats are supported directly through iBooks this way.
Interestingly, the iPad supports competitor e-book apps, like the Kindle App, that allow users to read their Kindle-purchased books (in the .azw format) on iPads, iPhones, iPod touches, and any other iDevice.
Marketshare
Steve Jobs claimed Apple sold 5 million titles to over 2 million users through iBooks, back in June 2009, with the average customer purchasing 2.5 books per iPad. At the time he said this represented 22 % of the e-book market, forgetting that this only represents the titles sold through publishers that signed up with Apple, ignoring a few major publishers (notably Random House) and lots of smaller ones, too.
Currently, the iPad represents 32% of the e-reader market in a recent survey, second only to the Kindle.
Conclusion/Review
The iPad is a mixed bag on the DRM front. On one hand, the iBooks app supports the ePub format legitimately, without any crazy work-arounds as on the Kindle device. However, it continues to sell some books directly with the protection included, which at least it labels in the "Info" section. The "five computers per purchase" is also a little odd, considering the amount of computing devices consumers use these days and the fact that the iBooks storefront is only available on Apple products (but iTunes is available for all computers).
Apple also allows e-book competitor apps on its devices, like the Kindle one and the Kobo app. Theoretically, it is at least possible to get every kind of e-book format onto the iPad, but you have to download the appropriate application, which can be a drag for some people.
In spite of some weirdness on the DRM front, sales of e-books on the iPad seem to be increasing, but one has to wonder how much better Apple could perform by sticking to one format and not supporting seven different apps for different seven different formats.
