I've just released the latest version of PlainBox. The 0.5b1 release is available on pypi. A list of changes, and a lot of other documentation, is available on readthedocs. This release was long in the making, bringing a number of important features and bug fixes.
Updated Debian packages should be made available tomorrow. The final release is expected early next week after which I will try to get a Feature Freeze Exception and sync it to Ubuntu 14.04.
About PlainBox: PlainBox is a toolkit consisting of python3 library, development tools, documentation and examples. It is targeted at developers working on testing or certification applications and authors creating tests for such applications.