This would be great to see fixed. It's perplexing to have discussion => 0 in my configuration, not have any discussion links on my site, but still be able to add a discussion page by URL hacking something like this: /cgi-bin/ikiwiki/ikiwiki.cgi?page=posts%2Fdiscussion&do=edit.

spammers have figured that little trick out so I am consitently getting spammed checked into my git repository.

I'm not really sure if this patch introduced other problems, but it seems to have fixed my site:

    0 mcclelland@chavez:~/.ikiwiki/IkiWiki/Plugin$ diff -u /usr/share/perl5/IkiWiki/Plugin/ 
    --- /usr/share/perl5/IkiWiki/Plugin/   2012-05-07 11:31:24.000000000 -0400
    +++   2012-07-29 17:49:28.000000000 -0400
    @@ -25,7 +25,7 @@
        my $cgi=shift;
        my $session=shift;

    -   return "" if $page=~/(\/|^)\Q$config{discussionpage}\E$/i;
    +   return "" if $page=~/(\/|^)\Q$config{discussionpage}\E$/i && $config{discussion};
        return "" if pagespec_match($page, "postcomment(*)");
        return undef;
    1 mcclelland@chavez:~/.ikiwiki/IkiWiki/Plugin$  

If libdir is configured to be ~/.ikiwiki in your ikiwiki.settings file, and you are running Debian, you can do the following:

    mkdir -p ~/.ikiwiki/IkiWiki/Plugin
    cp /usr/share/perl5/IkiWiki/Plugin/ ~/.ikiwiki/IkiWiki/Plugin/

And then apply the patch above to ~/.ikiwiki/Ikiwiki/Plugin/