Let's face it:
FireWire is on its way out due to USB's huge dominance... if it's not discontinued now, it will be eventually. It will join the ranks of all the other discontinued proprietary formats like Atari, Commodore, Amiga, VHS, Betamax, DivX, HD DVD, and so on.
Firewire (aka IEEE 1394) is not proprietary. And it meets needs that USB does not.
It is isochronous, and supports high-end digital camera and camcorders better, with higher stability (less 'jitter' than USB).
It also doesn't force you to think about hosts and targets, and worry about whether the connector will fit. USB forces you to worry about which device is the host, and which is the target.
Connect PDA to PC - works OK.
Connect Scanner to PC - works OK.
Connect PDA to scanner - Hmm..
With firewire, this isn't an issue. As a result, I've been advocating firewire for interconnecting software-defined radio components for some time.