So at miscon GRRM read two chapters from the upcoming book and then he started answering questions. Some girl eventually asked him what did Brienne yell out? Well he then went on to ask the crowd if they figured it out and everyone started yelling things and then eventually someone guessed it. "Sword" and by that she meant that she picked to swear her sword to Lady Stoneheart. Then the girl asks about Pod and GRRM answers that Brienne did it to save the innocent life of Pod. The theory is that now Brienne is taking Jaime into some type of trap/ambush. I guess a lot of this could have been guessed already but at least there is confirmation that Pod is alive.