/usr/local/lib/liblabjackusb.dylib: mach-o, but wrong architecture
You have a 32-/64-bit problem. From what I can infer, you compiled the Exodriver yourself. When you compile it yourself with the default Makefile, you build a 64-bit Exodriver. Confirm this by running:
$ file /usr/local/lib/liblabjackusb.dylib
/usr/local/lib/liblabjackusb.dylib: Mach-O 64-bit dynamically linked shared library x86_64
This usually isn't a problem (it's how I have my current Exodriver), unless you need to use it from a 32-bit application. Snow Leopard comes with a combined 32- and 64-bit Python:
$ file /usr/bin/python
/usr/bin/python: Mach-O universal binary with 3 architectures
/usr/bin/python (for architecture x86_64): Mach-O 64-bit executable x86_64
/usr/bin/python (for architecture i386): Mach-O executable i386
/usr/bin/python (for architecture ppc7400): Mach-O executable ppc
So my guess is that you're using a different installation of Python, one that you downloaded and installed yourself. The one from python.org, for example, is 32-bit only. Does this sound familiar? What do you get when you run?
$ which python
If it's not "/usr/bin/python", what do you get when you run?
$ file `which python`
To fix the problem, you have at least two options. First, you could use the built-in python. That would require reinstalling LabJackPython where the built-in python can find it. Run something like
$ cd path/to/LabJackPython/src
$ /usr/bin/python setup.py install
Second, you could install a combined 32-/64-bit Exodriver and replace the 64-bit only version you have. Compiling the Exodriver for both platforms is easy (just edit one line in the Makefile), but the Exodriver depends on libusb, and compiling libusb for 32- and 64-bit systems is harder. Fortunately, we did the work for you. The "Exodriver (native USB) Mac OS X installer" on this page:
contains 32-/64-bit copies of the Exodriver and libusb. You should remove the copies you have already (in /usr/local/lib) to be safe if you want to use this installer.