On Sun, 9 Dec 2007, grid@bmk.com.au wrote:
>> How-To-Repeat:
> 1.) # halt
> 2.) Wait for "The operating system has halted"
> 3.) Press power button (no response)
> 4.) Press and hold power button for 5 seconds (turns off)

This is expected behaviour. Have you tried 'halt -p'? From the man page:

  -p      Attempt to powerdown the system.  If the powerdown fails, or the
          system does not support software powerdown, the system will halt.
          This option is only valid for halt.

Cheers,
Jared