Great question!
If that were true, yes, we could use all the external battery packs we've accumulated over the years...my favorite is the Trent Cruiser, which holds a massive charge. And immediately, there goes any concern about battery life on the Pro.
But...
I would guess the answer is no. I think that even though smartphones and typical tablets get power through the same port that they sync, I am inclined to believe ours cannot do the same. Plus, I would be concerned about frying the unit - by putting power in the wrong port.
I hope one of the true Surface experts can help.