The new Pages 7.3 released today gives writers the ability to publish a book directly from Pages to Apple Books. The new option in the File menu hooks directly into your iTunes Connect account if you have set yourself up as an Apple Books creator. Previously Apple offered a separate app, iBooks Author for this, which is still the only way to produce books that use some advanced features.
In addition to Pages, Apple updated Numbers and Keynote with big fixes. GarageBand has an update specific to the iPad Pro, and iMovie will now make use of external displays through the iPad Pro’s USB-C port. iMovie on Mac has lost the ability to share directly to Facebook, probably as part of Apple disconnecting users from Facebook’s systems over privacy concerns. You can still output in a Facebook-friendly format and then upload via the web.