Collum’s Song

I was listening to a rebroadcast NPR’s Mountain Stage this week, and heard Nellie McKay doing an absolutely wonderful version of a tiny little gem called “Collum’s Song.” (On NPR’s publicly available big whole-show MP3, it goes from 24:10 to 25:50: one minute and forty seconds of fine figurative language, nicely sung. I won’t put it up here, but the song alone makes for a very small 1.5 MB MP3 file that shouldn’t be too much trouble for most email clients.) My question, though: where is it from? I’m otherwise not much of a McKay fan, but I couldn’t find this on any of her albums, and the wordplay and imagery is rather a departure from what little I know of her usual fare. Anybody know it?