I've done some probing around and have some preliminary info on the connector to share. I used a Fluke 189 dvm and a Tektronix 2252 scope.
First order is to identify pin 1. I'm assuming that when viewing the connector with the screen up, pin 1 is on the left.
Pins 1 and 6 are ground. Zero resistance between the two.
Pin 2 is a control pin. Open circuit voltage is 1.12 V. If you pull it down with a 1.5K ohm (minimum) resistor momentarily and let it go up, the Nexus 10 powers on. (Discovering that was good for excitement ...) Once powered on, if you pull it down again, Nexus goes into clock mode. Obviously meant for a dock. Don't know if this pin does other tricks. Note that the picture of the pogo charger connector shows pin 2 missing.
No clues about pins 3-5. One is obviously +5 for charging. But I'm not ready to apply power to unknown pins yet. Seems to me that since there's a charger floating around, it would be better to wait for someone to check out its pins.
Pins 3-5 are near ground level. No pull-ups, clocks, etc.
I had no luck finding audio on any of the pins. There might be a control function that mutes the Nexus speakers and enables audio. Or it might happen when you supply charging power.
I hope that there are some brave souls out there that could help identify more pins. The charger is the most important because it might enable other pins.