My wife gave me a scare a few days ago by announcing that the Oxford comma had been dropped from the Oxford Style Manual. As it turns out, this was a false alarm caused by the failure of the University Press's P.R. firm to use one in their announcement of the Manual's latest edition. Silly monkeys.
So, what is this Oxford comma, and why does it matter? (Hint: there's one in the caption of this post.) You won't get the answer by watching the video above, and listening to the lyrics of a song called "Oxford Comma" by Vampire Weekend, one of my favorite twee bands (the other is Belle & Sebastian). You will by reading this NPR piece by Linda Holmes, whose views on language issues appear virtually congruent with mine (although I do hyphenate "e-mail"). She concludes by noting that all of us who care about such things have our pet peeves. If you've been following this blog for a while--and if you have, God bless you--you know mine.
Update: reader Quin, in a comment below: "A battle rages in my firm over this--it's AP v. Oxford." I'm guessing you're on the Oxford side, Quin, so you may cite the Chicago Manual of Style (16th ed., 2010) 6.18 as support:
When a conjunction joins the last two elements in a series of three or more, a comma--known as the serial or series comma or the Oxford comma--should appear before the conjunction. Chicago strongly recommends this widely practiced usage, blessed by Fowler and other authorities (see bibliog. 1.2), since it prevents ambiguity.