The New York Times had a very interesting article on morality in primates. As many primates display empathy, understand who has done them favors, display altruistic behavior and take into consideration the greater good of their group when resolving disputes, they are displaying some of the required building blocks for morality.

You can read the entire article at:
http://www.nytimes.com/2007/03/20/science/20moral.html?ref=science