Tim Harford at the Financial Times finds le mot juste -- not grade inflation, but grade distortion:
Grade distortion is a serious affair. Students and their teachers are forced to switch to grey market transactions denominated in alternative currencies: the letter of recommendation, for example. Like most alternative currencies, these are a hassle.
Grade distortions, like price distortions, destroy information and oblige people to look in strange places for some signal amid the noise. Students are judged not on their strongest subjects A grade, of course but on whether they also picked up A grades in their weakest. When excellence cannot be displayed, plaudits go instead to those who deliver pat answers without stumbling politicians in training, presumably.
Via Lone Gunman.