The only thing I use FireWire for, Target Disk Mode, cannot be done with USB. This omission has made the new MacBooks a lot less appealing.
Or perhaps someone will write an os x driver to take advantage of usb-usb (aka usb bridge / networking) cables that work for PCs.
http://en.kioskea.net/faq/sujet-345-how-to-connect-two-compu...
The advantage of these solutions is that you can work with other non mac os x computers.
http://en.wikipedia.org/wiki/FireWire#FireWire_S800T_.28IEEE...
put that on a boot cd and you're all set.