As far as I know when running a Python script: python myscript.py, Python would by default include the script directory to the sys.path (in fact it should be sys.path[0]).
On my machine (Mac OS 10.6.3, running Python 2.5.4) I do see a different behavior where the script itself is set as sys.path[0] instead of its directory. As you can imagine this breaks all imports.
Do you have any idea what would've changed on my system to have this (wrong) behavior?