http://blogs.msdn.com/opal/archive/2008/01/23/faceted-search-2-0-for-sharepoint-search-server.aspx
http://blogs.msdn.com/sharepoint/archive/2008/01/30/open-source-faceted-search-for-moss-2007-and-microsoft-search-server-2008-part-1-of-2.aspx