I don't think they're USB, although it's entirely possible they hook into the USB bus internally like on some PC systems. Without a pinout it's more or less impossible to say without one hooked into a system sitting in front of me.

I decided at such a good price I might as well order one and see if it works. I figure if it does/does not work at least I can report back what happened so other MDD FW800 owners will know whether they are wasting their money or if this is a viable upgrade pathway to install Bluetooth 2.0 into their G4 systems.

One more bit of knowledge for the community is worth a few bucks.