This is available via the software update
This update addresses issues in Keynote, Pages, and Numbers, and adds export compatibility to Pages with the standard ePub file format (for use with iBooks).
This update is recommended for users of iWork 9.0, 9.0.1, 9.0.2, and 9.0.3. For detailed information on this update and individual application changes, please visit this site: http://support.apple.com/kb/HT4165.
