Celebrated by both the Horde and the Alliance, the Harvest Festival is a time to commemorate those who have sacrificed their lives to help their allies. The Alliance honors the memory of all the fallen, but most especially Uther Lightbringer. The Horde also remembers those who have fallen, with special emphasis on the memory of Grom Hellscream.
The Harvest Festival event, which runs from September 24th to 30th, starts in Ironforge and Orgrimmar, for the alliance and horde respectively.
Read here for more information.
http://www.worldofwarcraft.com/info/eve ... tfestival/