What do the "Pogo Pins" on the Galaxy Nexus map to? I'd like to make my own doc similar to below. The official one for $90 doesn't come with a power adapter so I assume you just plug the USB charger into it. What pins from USB map to the three pins in the photo?
Someone over at AndroidCentral built their own charging dock.  According to the post,


  ... the pin closest to the bottom of the GN is the 5V and the pin
  closest to the power button in the GND.


It is assumed that the middle pin is for letting the phone know it's connected to the dock and launch the needed activities (enable Bluetooth, launch apps, etc.)