Ah ha! You're correct: there's something wrong with the file I was
generating from. The problematic file had come packaged with designs
for the project I'm working on. I used it because I knew we had a
licensed copy of Myriad Pro Condensed somewhere on our server at work,
but didn't want to go digging around to find it. But after your
suggestion I did just that, generated a new Cufón file, and now the
example works perfectly.
Sorry for the false alarm, and thanks for your help, Simo!
- Mark