Importlib is now on the Cheeseshop. I took what was in the trunk for Python 2.7 and tossed it up. At the moment I know it can go as far back as Python 2.5, but I bet it will go back even farther without issue; just need to get my hands on older interpreters to see how compatible it is.
With import_module() one does not need to call __import__ and try to comprehend how to use it. Instead you use import_module() and get a much saner API.