I recently installed the new Arch Linux image (archlinux-hf-2012-09-18.zip) from http://www.raspberrypi.org/downloads.
One of the first steps I did was to set the correct timezone for the device.
The default is “Europe/London” but since I live in Austria I wanted to change this to “Europe/Vienna”.

As Arch Linux changed to systemd, setting the correct value in /etc/rc.conf didn’t help – in fact, the file didn’t even exist.
Turns out the timezone is now set with the command timedatectl
A simple run of this command returns the following on my system:

[root@alarmpi etc]# timedatectl 
      Local time: Tue, 2012-10-30 21:28:18 CET
  Universal time: Tue, 2012-10-30 20:28:18 UTC
        Timezone: Europe/London
     NTP enabled: no
NTP synchronized: no
 RTC in local TZ: no

Changing the timezone is easy, just use the following syntax (change “Europe/Vienna” to your value)

timedatectl set-timezone Europe/Vienna

If you get the error

[root@alarmpi etc]# timedatectl set-timezone Europe/Vienna
Failed to issue method call: The name org.freedesktop.PolicyKit1 was not provided by any .service files

make sure you install the polkit package like

pacman -S polkit

After installing the package reboot your device – without rebooting you will get an “Access denied” error. Thanks to Sandybanks for pointing this out