This probably isn't a hint so much as a, "Hey, I just figured something out": In Apple Mail's built-in RSS reader, you can view the author of a story in an RSS feed: Right-click on the bar with column-headers on it (Subject, Date, etc) and select "Author." Adjust the columns to fit your preferences.

As far as I can tell, this is the only time you can select that Author headling; if you're in a regular mailbox, it is grayed out.