little mistake, not really a bug
I guess you had some kind of rewrite or defined gforum.cgi as index file in the "old version".
Nevertheless as far as I can see there is a mistake. I used to start at
http://www.gossamer-threads.com/perl/gforum/ which still shows the index page of the forum but you cannot go anywhere because there is 404
I do have seen that it works with http://www.gossamer-threads.com/perl/gforum/gforum.cgi
But I do like the first impression of the redesign of your site
n || i || k || o
Nevertheless as far as I can see there is a mistake. I used to start at
http://www.gossamer-threads.com/perl/gforum/ which still shows the index page of the forum but you cannot go anywhere because there is 404
I do have seen that it works with http://www.gossamer-threads.com/perl/gforum/gforum.cgi
But I do like the first impression of the redesign of your site
n || i || k || o