Shutdown and Restart from the command line.

I had some problems recently where two OSes (Ubuntu Intrepid Alpha 3 and KuruminNG) did NOT shutdown by means of the panel icon. Instead in both cases I was brought to the login screen. Of course, here I could select Restart from the menu but it was a bit of a roundabout way to reboot.
However, there are CLI commands you can use to shutdown and startup as follows:

Shutdown

sudo init 0

Restart

sudo init 6

Of course, you could always make a small script to execute these commands from an icon, if necessary.