http://esupport.sony.com/US/perl/swu-list.pl?mdl=PRS505
Ryder35, I found that by doing a Google. I am awaiting my 505 from Waterstones and wanted to know what I might need to do to update. Please read the FAQs or the Troubleshooting forum here before applying the update just in case.
From another mobileread member: "Mine is a UK release so it should be up to date. the firmware is 1.2.00.18050" Note that this firmware is newer than that shown on the Sony site above.