First bug was mine. I was doing "import Adafruit_BBIO as GPIO" instead of "import Adafruit_BBIO.GPIO as GPIO". That gave this error once I started trying to use it:
$ ./test.py
Traceback (most recent call last):
File "./test.py", line 5, in <module>
GPIO.setup("P9_11", GPIO.OUT)
AttributeError: 'module' object has no attribute 'setup'
$ ./test.py
Traceback (most recent call last):
File "./test.py", line 5, in <module>
GPIO.setup("P9_11", GPIO.OUT)
AttributeError: 'module' object has no attribute 'setup'
The other bug was theirs: the code appeared to be working, but the GPIO pins weren't changing state. Turns out there's no error checking in the library (ugh). So it wasn't giving any errors when I failed to run the script as root.