I just released zope.interface 3.5.2, which adds only this bug fix: - BaseAdapterRegistry.unregister, unsubscribe: Remove empty portions of the data structures when something is removed. This avoids leaving references to global objects (interfaces) that may be slated for removal from the calling application. I've made a source distribution available via PyPI: http://pypi.python.org/pypi/zope.interface/ Windows users would likely be thankful if someone with the appropriate tools and know-how to build Windows binary distributions were to do so and upload those to PyPI as well. Enjoy! -Fred -- Fred L. Drake, Jr. <fdrake at gmail.com> "Chaos is the score upon which reality is written." --Henry Miller