Regarding the taped up "mystery port" located on the Macbook Pro...
Now that we have the MCP79 chipset from Nvidia (which I assume will be used in both the Macbooks and Macbook Pros)... What if that "port" is actually a switch?
From what I read earlier, the MCP79 chipset supports HybridSLI, which to my understanding is, being able to switch between discrete and integrated graphics (albeit a computer restart would be required). The point of this being, high-end graphics would be used when its needed and integrated graphics would be employed when high-end graphics are not needed which will, in turn, increase battery life.
So going back to the switch... I know Sony notebooks (among others probably out there...) have a little switch to toggle between integrated (stamina) and discrete (speed) graphics. I think the picture attached speaks for itself...