I guess I'm a
pedant traditionalist when it comes to the word "data": one "datum", several pieces of "data", etc.
As with many matters relating to the use of language, though, this one isn't open and shut, by any means.
And so a few days ago we saw The Wall Street Journal, The Economist, and The Guardian grappling with this issue once again.
However, I'm going to stick with my guns, dust off my slide-rule, and also continue to use the "Oxford comma"!
© 2012, David E. Giles