Vampire Weekend predicted this years ago: the University of Oxford no longer cares about their own comma...

As a general rule, do not use the serial/Oxford comma: so write ‘a, b and c’ not ‘a, b, and c’. But when a comma would assist in the meaning of the sentence or helps to resolve ambiguity, it can be used – especially where one of the items in the list is already joined by ‘and’...

UPDATE (via kottke.org): The text quoted above comes from Oxford's internal style guide, not their published for-public-consumption manual of style.  So, basically, they've stopped taking their own advice.  E.B. White, being dead, remains unmoved in all this:  "In a series of three or more terms with a single conjunction, use a comma after each term except the last."