Just like announced, Blizzard will release a series of stories related to the Leaders of the Alliance and Horde.
The first story in this series, "Heart of war", offers a look at the experiences that have shaped Garrosh into the leader he is today: his heroic exploits in Northrend; his uncertainty upon reaching the imposing capital of Orgrimmar; and more importantly, his friendship with his mentor, the warchief he would eventually replace, Thrall. This story was written by Sarah Pine, the winner of Blizzard Entertainment's 2009 Global Writing Contest.
You can read the story here: download it PDF format.