One important gotcha is a special case where non-python applications create Babel objects implemented in python. In this case, the Babel runtime needs to dynamically load the python virtual machine (libpython.so). Unfortunately, python does not always build a dynamically loadable version of this library by default. If the Babel configure script cannot find a libpython.so, it will disable server-side Python support.
At the time of this writing, Python cannot be coerced to build a libpython.so on AIX.