White Knight Chronicles: Awakening of Light and Darkness (a.k.a. White Knight Chronicles 2) has been revealed to take place right after the events of the first game.
In it, Leonard and his allies see that the City of Greed, the Kingdom of Barandel, and the Magic Republic of Foria are in big trouble.
Also, according to Joystiq, you'll create another avatar to join Leonard and be able to transform, explore new areas, battle more monsters, and new equipment and skills will be added as well.
There's also feature a new female knight, and you're able to have six characters in your party.