It took me a while to track down this info, so I figured I'd share it here to save anyone else the time.

You can read Google Groups discussions as RSS feeds using the RSS Feed widget or other readers. Use this URL:

https://groups.google.com/group/Google-Group

Just switch out "Google-Group" with the name of the group that you want to read. If the name includes spaces, then replace them with dashes (-).

More information is here: http://webapps.stackexchange.com/questions/33354/how-do-i-follow-a-google-group-using-an-rss-reader