RSS = Really Simple Syndication. It's a way to get information about what's happening in one area of the web, and display it somewhere else. There are standalone RSS readers, or you can use IE7 or Outlook 2007.
For example, here's a link to the RSS feed for the MFG home page (which is now stale, since it's driven from the old MFG 4 forum):
http://mfgforums.com/forums/rss.aspx?ForumID=134&Mode=0