Yes. Or better to say, I tried it and works. I tried it with openSUSE 10.2 and an external HDD. But as Peg2 is my only machine with firewire, and I also have USB2 I don't even know where my firewire cable is any more. Of course, if you need some help, I can try to find it :-)
Oops, almost forgot: I used Peg2 with openSUSE 10.2 to download some recordings from a DV camera (which I had only for a few weeks to film the baby :-) ). For this I used 'kino' from packman, which is available for PPC at
ftp://spike.fa.gau.hu/pub/pmppc102/