/etc/httpd # tail -f /var/log/httpd/error_log
[Sat Sep 29 09:21:41 2007] [notice] suEXEC mechanism enabled (wrapper: /usr/sbin/suexec)
[Sat Sep 29 09:21:41 2007] [warn] module auth_pam_module is already loaded, skipping
[Sat Sep 29 09:21:41 2007] [warn] module auth_sys_group_module is already loaded, skipping
[Sat Sep 29 09:21:41 2007] [notice] Digest: generating secret for digest authentication ...
[Sat Sep 29 09:21:41 2007] [notice] Digest: done
[Sat Sep 29 09:21:41 2007] [notice] mod_python: Creating 4 session mutexes based on 256 max processes and 0 max threads.
[Sat Sep 29 09:21:41 2007] [notice] Apache/2.2.6 (Unix) DAV/2 mod_python/3.2.8 Python/2.4.4 SVN/1.4.3 configured -- resuming normal operations
[Sat Sep 29 09:23:09 2007] [error] [client 75.67.207.132] PAM: user 'daniel' - not authenticated: Authentication failure

/etc/httpd # cat /etc/pam.d/httpd
#%PAM-1.0
auth       include      system-auth debug
account    include      system-auth debug

/etc/httpd # cat conf.d/auth_pam.conf
LoadModule auth_pam_module modules/mod_auth_pam.so
LoadModule auth_sys_group_module modules/mod_auth_sys_group.so

/etc/httpd # ls -all modules/mod_auth_pam.so
-rwxr-xr-x   1 root     root         6148 Sep  4  2006 modules/mod_auth_pam.so
/etc/httpd # ls -all modules/mod_auth_sys_group.so
-rwxr-xr-x   1 root     root         5200 Sep  4  2006 modules/mod_auth_sys_group.so

Note I've also tried chowning the above to apache:apache with no success.

#httpd.conf
<VirtualHost *:3050>
   ServerName cianaidansys.com
   DocumentRoot /srv/trac/cianaidansys
   SetEnv TRAC_ENV "/srv/trac/cianaidansys"
   Alias /trac/ /usr/share/trac/htdocs/
   <Directory /usr/share/trac/htdocs>
       AllowOverride None
       Order allow,deny
       Allow from all
   </Directory>
   ScriptAliasMatch ^/(.*) /usr/share/trac/cgi-bin/trac.cgi/$1
   <Location "/">
       AuthType Basic
       AuthName "Private Cianaidan Trac"
       AuthPAM_Enabled On
       Require valid-user
   </Location>
</VirtualHost>