Changing the time zone in Ubuntu Server


I changed the time zone of my server (Ubuntu 12.04) to UTC via:

echo 'UTC' > /etc/timezone
dpkg-reconfigure --frontend noninteractive tzdata

When running date, I can see the time is now in UTC. However, on /var/log/syslog, it still displays the time with the previous setup timezone and not UTC. Why? How to make it take effect on the whole system? Reboot?