The Navigator SDK for PDF Portfolio Layouts is finally out of beta and is available for download. Samples, updated documentation and other resources are available in the Acrobat 9.1 SDK August 2009 update. You can get it by following the link below.
NOTE: If you have already created navigators for your PDF Portfolios, it is highly recommended that you replace the AcrobatAPI.swc file in your project, recompile and update your .NAV files. Be sure to increment the “version” attribute in your navigator.xml file to make applying your updated navigator to your existing PDF Portfolios.