I have wondered about this for some time, so what's the answer? For example, if the ping command is issued via a terminal window is it routed through Tor via TAILS?

Except for hosts in the local network (RFC1918 classes), all traffic is redirected to the Tor network using system-wide firewall rules. Please note that Tor does not handle ICMP traffic which means that using 'ping' will not have any significant outcome.
Comment by Anonymous Mon 31 Oct 2011 05:50:38 PM CET

Hi, Tails is using an in depth strategy in order to route all the outgoing traffic through Tor. First, the main applications: web browser, email client, instant messaging application, etc. are explicitly configured to use Tor but on top of that there is also a firewall that works as a transparent proxy routing all outgoing traffic to go through Tor even if the corresponding application is not configured to do so.

As said before, 'ping' will not work in Tails but that would be the case if you'd use the 'ssh' command for example.

Comment by Tails Tue 01 Nov 2011 10:27:37 AM CET