I’ve been told that there was no notification features for Radio site editors who want to know when and where a comment has been posted.  It seems that since the discussion board Radio uses at http://radio.userland.com/discuss/ has this feature as a checkbox that enables
“Receive direct responses to the message on this page via email.”  ,  there should be something similar for comment posts.   I already have,  after just a few days,  way too many posts to easily spy new comments,  not to mention any attached to already archived articles.