Python libusb pyusb "mach-o, but wrong architecture"

I am hav开发者_开发百科ing some trouble with the pyusb module. I have narrowed down the problem to a single line, and have created a small example script to replicate the error.

#!/usr/bin/env python
"""
This module was created to isolate the problem in the pyusb package.

Operating system:  Mac OS 10.6.3

Python Version: 2.6.4

libusb 1.0.8 has been successfully installed using:
sudo port install libusb

I have also tried modifying /opt/local/etc/macports/macports.conf to force
the i386 architecture instead of x86_64.
"""
from ctypes import *
import ctypes.util

libname = ctypes.util.find_library('usb-1.0')
print 'libname: ', libname
l = CDLL(libname, RTLD_GLOBAL)

# RESULT:
#libname:  /usr/local/lib/libusb-1.0.dylib
#Traceback (most recent call last):
#  File "./pyusb_problem.py", line 7, in <module>
#    l = CDLL(libname, RTLD_GLOBAL)
#  File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/ctypes/__init__.py", line 353, in __init__
#    self._handle = _dlopen(self._name, mode)
#OSError: dlopen(/usr/local/lib/libusb-1.0.dylib, 10): no suitable image found.  Did find:
# /usr/local/lib/libusb-1.0.dylib: mach-o, but wrong architecture

# End of File

This same script runs on Ubuntu 10.04 successfully.

I have tried building the libusb module (directly from source AND through macports) for 32-bit (i386) instead of x86_64 (default for OS 10.6), but I receive the same error.

Thank-you in advance for your help!