Open Source Applications Foundation (OSAF) released Chandler 0.6 on December 20, 2005. Chandler 0.6 includes an “experimentally usable” calendar, with support for recurring events, time-zones and the ability to share calendars with others.
Chandler is a Personal Information Management (PIM) client application with innovative design and ambitious plans for sharing, extensibility and cross-platform support. Chandler is written mainly in Python.
There is a wealth of information about the application and this particular release at the Chandler 0.6 Home Page: