Curtains are hung and people are hanged.
A couple of months ago I used the word hung wrong in the podcast about the man who invented the guillotine, so today I’ll review the proper use in case I confused people.
The standard quip is that curtains are hung and people are hanged. It's not quite that cut-and-dried*—some of my reference books say hung isn't wrong, just less customary, when referring to past executions, and the Random House Unabridged Dictionary says that hung is becoming more common—but the majority of my books agree that the standard English past tense of hang is hanged when you are talking about dangling people from a rope, and in other cases, it’s hung.
It seemed curious to me that there would be two past-tense forms of the word hang that differ depending on their meaning, so I did a little research and found out that in Old English there were two different words for hang (hon and hangen), and the entanglement of these words (plus an Old Norse word hengjan) is responsible for there being two past-tense forms of the word hang today (1).
1. Burchfield, R. W., ed. The New Fowler's Modern English Usage. Third edition. New York: Oxford, 1996, p. 349.
* This is an idiom that refers to the practice of cutting wood and letting it dry out thoroughly before using it in a fire, according to the Morris Dictionary of Word and Phrase Origins. (Web reference)
[Note: This article was updated October 5, 2014.]