Apple has released version 9.0.4 update to iWork comprises bug fixes to Keynote, Pages and Numbers. New in this release is the support of ePub format in Pages. Pages is the first commercial word processor that can export documents in ePub format, alongside PDF and Word. ePub format will allow you to read the document in iBooks or other eBook reader software supporting ePub.
Check out [Apple’s support document](http://support.apple.com/kb/HT4168) which explains the differences between PDF and ePub. It also contains guide and template on how to create ePub document using Pages.
This update is available via the usual Software Update or you can download from [Apple Download site](http://support.apple.com/downloads/).