Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
It can charge from any of the ports, it does not charge from all of them. The port with the highest power source will be chosen, not sure how it decides if they are the same.
 
You can charge from any of the ports on either side, but only from one at a time; you cannot plug in two chargers for example and expect it to charge faster or anything crazy like that.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.