Updating this for the sake of a bit more completeness for those running across the thread in the future. I posted this in response to another thread, but putting it here too. Will post again when my other LCDs turn up.
This was the board I ultimately came up with for mine. Still waiting for the second LCD to arrive in the mail to give it a full testing though. But, it works with one LCD hooked up to either sockets, and it's recognising which socket the LCD's hooked up to and sending the appropriate output.
The 4N25's are just to hook up to a camera for AF+Ground and Shutter+Ground connections. The light coloured lines are just wires to bridge gaps (working on single sided board).
Using Raron's library - http://code.google.com/p/arduinoshiftreglcd/
No modifications needed, hopefully. We'll see when my other LCDs show up, but for now this is how they're declared...
ShiftRegLCD lcd(3, 2, 4, 2, 0);
ShiftRegLCD lcd2(3, 2, 5, 2, 0);
Then lcd.print sends to one output, and lcd2.print sends to the other. Like I said, it's sneding the output to the right set of pins when I switch the LCD over from one to the other, but still need to test running two at the same time.