I was going to post the map
Episode 217 was very interesting, and the fact that their hostage is one of the others will probably help them to find a lot of new information. The fact that there are other hatches is interesting and poses the question of how large the island actually is, and whether there are other hatch operators. The map clearly shows the possibility of there being a central station which connects all of the hatches together, and it is becoming apparent that they are not as isolated as they think, the blast doors and power outage giving time for a plane to be flown in and supplies dropped. The map was probably not meant to be seen by john, and if the speakers worked properly he would have probably been instructed to go into the room with the computer before the count down ended. Linking back to another episode, after the timer ranout, there were Egyptian symbols on the timer which must have some meaning. In a way, it is possible that the timer serves as a signal to the operators of the dharma initiative so they know if they are in trouble, ie they cannot type in the code.
Edit: I forgot to mention the chances are the map on the door will not be shared with the hostage, and that they will probably try to put the ultraviolet lights back on and so the saga will continue...