net-mail/mailman will install even if www-servers/apache doesn't have cgi or cgid installed. This may be an issue with virtual/httpd-cgi not requiring certain APACHE_MODULES. Reproducible: Always
happened to me today. - www-servers/apache-2.2.17 - net-mail/mailman-2.1.14
Guys, please, tell us what USE flags are required (or better be enabled) in your package(s) to enable cgi support in them. www-servers/apache: apache-bugs@gentoo.org www-servers/lighttpd: www-servers@gentoo.org,wired@gentoo.org,hwoarang@gentoo.org www-servers/boa: www-servers@gentoo.org www-servers/bozohttpd: s4t4n@gentoo.org,www-servers@gentoo.org www-servers/cherokee: bass@gentoo.org,www-servers@gentoo.org www-servers/fnord: www-servers@gentoo.org www-servers/mini_httpd: www-servers@gentoo.org www-servers/monkeyd: www-servers@gentoo.org www-servers/nginx: hollow@gentoo.org, dev-zero@gentoo.org www-servers/resin: nelchael@gentoo.org, java@gentoo.org www-servers/skunkweb: python@gentoo.org, apache@gentoo.org www-servers/thttpd: www-servers@gentoo.org www-servers/tomcat: java@gentoo.org
tomcat: none. configuration based see http://tomcat.apache.org/tomcat-6.0-doc/cgi-howto.html
Pretty sure skunkweb doesn't support cgi.