If you'd think a little you realize there are many good reasons to include IP-over-1394 in this multi-platform oriented world we live in. Flexibility is always a good thing, imagine ... Ibook>PMac, XP>PMac, PMac>Linux and in my case ibook>Win2k, all at 400Mbs.
I can understand wanting as many options open as possible, and it would be nice to see IP over FireWire, but I don't think 10.1 has it--at least, I haven't heard so much as a peep about it, so I figure it's not likely included at this point.
Then again, I'll chime in with the "not necessary" crowd and point out that, if you're really doing networking, your chances of finding a client that doesn't have an Ethernet port but does have a 1394 one are pretty slim.
The one time FW networking would be nice is for quick, easy file transfer... and in that case, you don't really need IP. Since, as far as I know, FireWire disk mode should work under 10.1 (or 10.0 for that matter), you've got a decent chunk of the reason for simple networking even without FW-IP.
Haven't heard a peep, that's a shame considering Apple invented Firewire. AFAIK IP-over-1394 is rapidly becoming a solid affair; perhaps someone will port something over to OS X. Thats the really great thing 'bout X.