I now consider the simplification refactoring done in importlib. It is passing all of its own unit tests on top of working as the 2.6 importer and passing all of the 2.6 regression tests.
I have now started a text file that lists what is left to be done to get importlib into Py3K as the One True Import. Next on the list, the zipimport rewrite that triggered this refactoring job. =)