Re: Replacing the Chumby One screen?
Some sockets may have a switch built into them, so circuitry can be designed to behave differently when there is something plugged into them (e.g. mute/disconnect the loudspeaker when the user plugs in a set of headphones). I don't know whether that's the case with the Chumby socket which uses a different kind of plug than a headphone jack, but it's a fairly likely explanation for the extra terminals on the socket.
I suppose that would make sense - from what I've read, it seems to be used for insertion detection, I guess so that the device knows whether or not it's charging. Now to find where the wires go on the Chumby itself...