Google recently announced that you can view all the comments that Google News is offering from expert sources. (There’s not too many so sometimes it’s hard to find them.)
That’s interesting, but what Google doesn’t mention is that it’s using the source: syntax to find the commentary. So using the query source:google_news will find you all the expert commentary.
.. aaaand you can use keywords to search for only particular comments. source:google_news “global warming” hips you to just those experts commenting on global warming (all two of them.) Since these are standard Google News searches, you can use the RSS and Atom links on the left to make RSS feeds for them. Useful, if you’re interested in tracking expert commentary.