I was just watching the Dragonborn trailer again and if you look closely at the scene with the rieklings wielding spears pay close attention to the riekling at the back. If you watch carefully you can see he clearly throws it at the player. It passes the mounted riekling and lands to the players left. So spears CAN be thrown at least by enemies. Lets just say the player can use spears. Do you guys think the player character will (or should) be able to throw spears?
Dragonborn Trailer:
http://www.youtube.com/watch?v=TRmdXDH9b1s