Seems that this article wasn't very well researched, or at least the research is a bit stale:

"Alaska Airlines, JetBlue, United and Southwest do not charge for this nifty service. But others, including American, Delta and Continental, discourage the practice by tacking on a hefty fee — $150 to $250 — to reissue a ticket at a lower fare, which inevitably eats into the refund."

http://www.nytimes.com/2009/03/29/tr...racrefund.html