>I understand it is possible to force requirement of a login/pass for nntp
>posting. That method could make moderation and spam fighting easier, no?

It is possible, but it's a manual process.  The forums at http://forums.novell.com has had almost 10,000 registrations since February 11th and the cost/beneft to handle that isn't there.  The Novell forums have been running with NNTP since 1994 and there is no significant problem with moderation & spam fighting.  NNTP posts have a user ID and an IP address and can be handled almost as easily as a web forum post.  Keep in mind we're not talking about feeding USENET here.  There is no tie in from the Novell NNTP servers to USENET.