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In the journalism racket, that's called a serial comma. Salon, like most daily newspapers and, of course, the AP, uses something called AP Style, which omits the serial comma. Chicago Style, which is used by most magazines and in book publishing and academic writing, uses the serial comma.
When Salon was in its infancy, there were many long and exciting debates about style. Even after it was decided -- at my suggestion as Salon's first copy chief, I might add -- to use AP style, there was a faction
(coughGaryKamiyacough)
vainly trying to argue for retention of the "elegant" serial comma. That faction was defeated.