When I started working on my current project there was no physical story wall, instead the whole project was being tracked on Mingle. The current state of the Mingle story wall was sometimes visible on a shared monitor and sometimes wasn't, depending on whether or not the monitor had been turned off.
There was also a small wall used to track which stories were in development but after that there was no physical visibility of the status of anything.
The advantage of this approach was that there was no need to have the overhead of having to maintain a physical story wall and an electronic one.
The disadvantage was that it was quite difficult to see what people were working on and there was a very definite split between development and testing.
Mingle and similar tools are useful in distributed teams but they are information refrigerators in the sense that you have to put in some effort in order to get information from them – it's not immediately available to you.
The physical story wall on the other hand is an information radiator which is what we want!
In the case that we get around that problem by using a projector to beam the web page onto a wall I still don't think it's as effective because it's less human to deal with a projection than a real card wall.
I find it's much more effective for people to be able to move cards around with their hands and then move people in between those cards depending on what pairings make sense at any given time.
The collaboration on my team seems to have increased quite dramatically since we made the card wall physical and I'd be surprised if the overhead of updating Mingle and the story wall was more than 5 minutes per day.