Alan,
There are many choices available to set up your "mini network". It all comes down to how much you want to spend and what kind of performance you need.
On the high end there's Apple's "X-SAN". It can scale from three systems to 64 systems with many, many terrabytes of data, but it's NOT cheap and a little complex to set up.
On the low (or simple to use) end, there's solutions like Facilis' "Terrablock". Just do a google search for "FCP SAN" and you'll turn up plenty of information. The big differance in price is between "volume based" file systems and "file based". Once you dig deeper, you'll understand. If you workflow can handle the "volume based" limitations, that may be a cheap solution for you.
This is a very popular question, since network based workflows seem to be where editing is headed.
Good luck.
Mark