Ahhh... thanks for the link AK.
So there's actually 2 ways to get IP over 1394:
1. IPv4-over-1394, RFC-2734
2. The eth1394 kernel module supplied by the linux1394 project, which encapsulates ethernet packets with some other frame format (?) to shoot them out the 1394 connector.
Then there's this comment on that linux1394 eth1394 page:
One will be able to use this in conjunction with the ip1394 driver in Windows XP, and in Apple's upcoming IP Over Firewire implementation.
Which is cryptic to me; does this ip1394 Windows driver differ from both (1) and (2) above?