We have an Xserve hooked to one G5 and can mont it on our other boxes over gigabite ethernet. It works fine for DV and DV50 editing shared 3 ways. It will drop frames occasionally but for most editing it works fine. When a room needs to output then we have to be careful not to all hit the Xserver at the same time. I would think any fast local storage could be shared in the same way. Just be aware of the limits.
joe