Need info on firewire

Since in OSx you can use firewire as a networking device a user can send packets/pings. Could it be possible to use a firewire port to switch on and off electronics? For a example use a relay and send a packet/ping via terminal or script to make the relay switch on, then when the packet is finished receiving it turns off?

If it is possible then I have a killer project unfolding in my head.

I don't know enough of the FW spec to help you on that exactly, but I did find a bunch of USB controlled GPIO blocks that give you lines you can use to control relays. I'd doubt that FW ping would work as you're saying, cuz the ping signal would be a data stream, so it won't be a consistent voltage. This would mean your relay would be tripping on and off very fast. There may be something like this USB GPIO card available for FW if you really want to use FW.

GPIO Card:
<http://www.fivemanconspiracy.com/node/45>