i believe there is no google-defined attribute as author. rather, there are name and email which are sub-attributes of author and are all atom namespaces.
i believe the reason ebay is being seen in such results is simply by happenstance -- ebay submits their items with a custom-attribute author. none of those examples are accessing google's g:author -- which doesn't exist -- nor atom:name which contains the data.
-- You received this message because you are subscribed to the Google Groups "Google Base Data API" group. To post to this group, send email to google-base-data-...@googlegroups.com. To unsubscribe from this group, send email to google-base-data-api+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-base-data-api?hl=en.