Bulldog, I just managed to get my reader (505) working with my iMac again, I have reverted to Leopard, although my wife's reader works with her macbook and Snow Leopard.
Enter Finder and drag both Adobe Digital Editions and Sony eLibrary to the trash.
Reload ADE, when open click on the drop down menu to the right of the word Library. Select 'Authorise computer.' Reload Sony eLibrary.
Close ADe, leave Sony Library open. Connect your reader to the computer, monitor the status box, it should show your book being recognised, the reader will then show in the left hand pane. Download a book to the computer from your online store bookshelf. Activate the link, monitor the 'Status' box, you should see the bar gradually fill as the book file is transferred.
Good luck.