With the Oxford comma: We invited the strippers, JFK, and Stalin.
Without the Oxford comma: We invited the strippers, JFK and Stalin.
I was avoiding entering this conversation until I saw this example on the song linked by thenewgreen. Great example - one of many. I tell my students to use the comma as long as they are in my class and writing for me. I also tell them that if they use it once (as they inevitably do for the clarity necessary when discussing those famous strippers: JFK and Stalin) then to use it consistently. I understand that it's all a question of what habits were drilled into us by our iron-fisted grade 3 teachers who said that the comma meant "and." So why would we say and and? (deep sigh) This is a question of clarity, not mere preference. The spaces after a period are, however, a question of preference.