Originally Posted by KevinMXoom
The MicroUSB is still accessible on the side so you can just plug an MHL into that with the phone in the dock. There's no way three pins can carry enough data for HDMI video.
Yeah, that was my first thought as well when I saw only three pins in the original leaks.
USB requires 4 contacts minimum, and MHL uses the same connector. Four pins are 5V power and return, and ser+ and ser-.
Not sure what the three pogo pins on the GNex do, other than just power. Could be similar to those magnetic plugs that aren't polarized, so they can connect either way. Ground on outside two pins and voltage center, for example. Either way, it would nice if they would have added the capability to output signals through a dock.