Just like the news publishers, book publishing industry seems to be doomed. The convenience of eBooks is going to make paper books obsolete and once something is converted to soft format it is hard to control its spread. Consequently it becomes hard to exchange it for money.
eBooks that are sold DRM free, easily show up on rapidshare or filetube. Google bots make sure anyone with the skill of searching for "rapidshare " can get to these underground copies after few minutes of patient surfing.
Publishers that sell books with DRM, may make the book piracy difficult for general audience. But that only offers an opportunity to a single skilled hacker to prove how broken DRM is, and the outcome is again a freely available soft copy which makes its way to underground file servers.
Book publishers have to actively monitor web for the pirated copies and send take-down notices to the hosting services when they find them.
Given these facts, why don't eBook publishers explore other techniques of monetization? Coming to think of it, it will be so easy to give away ebooks for free and embed advertisements in them. ePub format is a dialect of html. Won't it be easy to just insert some ad markup into it. When I searched for eBooks with ads experiment I came across only one. The author used Yahoo's ad network and Adobe's software to ship some ads in the PDF ebook. But I guess it was just one-off experiment.
When you turn this idea over its head, it becomes what some authors are already doing. These authors publish their work on blogs over a period of time and at the end they package it in an eBook and give it away for free. The blog can be easily monetized with ads. The feedback over time can be used to improve the chapters along the way.