The changing meanings of words

Here's a link to an interesting article by Ben Yagoda on Slate.com about the changing meanings of words and the pros and cons of clinging to "old" meanings against a rising tide. What I found perhaps most interesting is the quiz he gave his students — university students in an advanced writing seminar — and their high rates of use, by overwhelming margins, of the "new" meanings of several common (some, such as nonplussed, might be somewhat uncommon) words.