<< yes there are firewire hubs & they cost $$$. You can just daisy-chain firewire together & save some money. I think you can daisy-chain up to 63 firewire devices together. The cable lenght limit is 15 ft between each powered firewire device.
At work, I have my firewire hard drive plugs into an external firewire Le Cie DVD-RW drive, which plugs into a Yamaha firewiire CDRW. >>
I guess if you were daisy-chaining, then your speeds would go down the way they did with those old 10Base2 and 10Base5(?) networks. Plus, you'd have to have all the computers on, and functioning properly. Sounds like too much trouble.