Taking another note. Here's how to change group owner for /var/www directory in Ubuntu Server 12.04. By default that directory meant to be DocumentRoot for Apache 2 web server and own by root. This practice is useful if we want to share the access to several people in webmaster group.

sudo addgroup webmasters

sudo chgrp -R webmasters /var/www

sudo find /var/www -type d -exec chmod g=rwxs "{}" \;
sudo find /var/www -type f -exec chmod g=rws "{}" \;

sudo gpasswd --add user webmasters
sudo gpasswd --add colleague1 webmasters
sudo gpasswd --add colleague2 webmasters
# etc.