I got this response:
Thank you for contacting Sony Support.
We're really sorry, but we do not have information on the Adobe Digital Editions Installer update that supports industry-standard eBook formats, including PDF/A and EPUB for the PRS-500. We have no prior knowledge of new updates until they are released by our Marketing Department. We suggest that you bookmark the following webpage and check periodically for any future updates:
http://esupport.sony.com/US/perl/swu...l=PRS500&LOC=3
Thank you for your time.
The Sony Email Response Team
C6EH
William