Jaina has changed her appearance before. Back in patch 3.3, she went from looking like a random human to getting her own model -- a much-needed change, but no in-game event was the basis for the update. In Mists of Pandaria, however, the events at Theramore seem to have put Jaina through enough to make her look rather battleworn.
The Battle of Theramore isn't officially implemented on beta servers yet. Sapperwix says there will be no new content with today's beta build, only the temporary removal of the Jade Forest, so it will be some time before we see this new Jaina in action.
What do you think of Jaina's new look?
It's open warfare between Alliance and Horde in Mists of Pandaria, World of Warcraft's next expansion. Jump into five new levels with new talents and class mechanics, try the new monk class, and create a pandaren character to ally with either Horde or Alliance. Look for expansion basics in our Mists FAQ, or dig into our spring press event coverage for more details!