Shade-throwing in the Middle Ages

I was listening to NPR this morning, and they posted a fascinating story about Pope Celestine V, one of the few popes who stepped down, rather than dying in office—and perhaps the only one, other than Benedict XVI, to do so voluntarily. Celestine, originally known as Pietro del Morrone, had been a hair-shirt-and-iron-girdle-wearing hermit in the Italian mountains before being crowned (arguably against his will) pope in 1294, and apparently intended to return to his previous lifestyle after resigning a mere five months later. Unfortunately, his successor was uneasy about the idea of two living popes and promptly had him arrested and imprisoned in a castle. Celestine died shortly thereafter, age 81. (He had a pretty good run for a dude in the 13th century, though.)

Anyway, here's the literary connection: apparently, in Dante's Inferno there's an unnamed figure in hell that apparently is widely believed to refer to Celestine:

I saw and recognized the shade of him
Who by his cowardice made the great refusal.
—Inferno III, 59–60

I wonder if Benedict XVI will be immortalized in a similarly nasty manner? Maybe he'll turn up as the villain of a Dan Brown novel.