Apple has released an update to iWork that in addition to fixing a handful of bugs, adds the ability to export Pages documents in the ePub format.
ePub is the open format Apple and many others use to publish ebooks but until now there has been no simple way for Mac users to create their own ePub content. In the updated Pages, ePub is listed as an export option, though only word processing documents are compatible; for layout documents, PDF remains the only and probably the best option.
The importance of this update is that it makes it easier for content created in Pages to reach users of iPad, iPhone and iPod via applications such as iBooks.
Apple's page on creating ePub documents with Pages is here.