Thanks for the link. Yes, it's true.

Judging from the comments at that site, I am not the only one who's mind went there!

This whole episode reminds me of the "Pope's Testicle Test" procedure. Or the "Due Testicoli!" test. Most relevent portion from wikipedia in bold print below:

Generally, there are two versions of the legend.

--In the first, an English woman, called Joan, went to Athens with her lover, and studied there.
--In the second, a German woman called Giliberta was born in Mainz.

"Joan" disguises herself as a monk, called Joannes Anglicus. In time, she rose to the highest office of the church, becoming a pope.

After two or five years of reign, Pope Joan became pregnant, and during an Easter procession, she gave birth to the child on the streets when she fell off a horse. She was publicly stoned to death by the astonished crowd, and according to the legend, removed from the Vatican archives.

As a consequence, popes throughout the medieval period were required to undergo a procedure wherein they sat on a special chair with a hole in the seat. A cardinal would have the task of putting his hand up the hole to check whether the pope had testicles.

In a seventeenth-century study, Protestant historian David Blondel argued that 'Pope Joan' is a fictitious story. The story may well be a satire that came to be believed as reality. This view is generally accepted among historians.