httpd.  My apache2 install worked as a Monticello
repository right out of the box on my RedHat 7.2 server.  For
posterity's sake, here's all I had to add to my apache2 config:
Alias /monticello/ /var/monticello/
<Directory /var/monticello>
  DAV on
  Options indexes
  Order allow,deny
  Allow from all
  AllowOverride None
  # Limit write permission to list of valid users.
  <LimitExcept GET PROPFIND OPTIONS REPORT>
    AuthName "Authorization Realm"
    AuthUserFile /etc/monticello-auth
    AuthType Basic
    Require valid-user
  </LimitExcept>
</Directory>
This gives a world-readable, authorized-user-writable Monticello
repository in /var/monticello.  I created /etc/monticello-auth with
htpasswd and off I went.  I love Monticello and look forward to future
improvements.