This plugin adds new navigation item "Calendar". Calendar is (or is aimed to
be) the tool for planning of tasks with associated date and time. E.g. ticket
to be solved, a conference to attend, or a call to be made can be planned with
Calendar. Items for given week are displayed in an overview with resolution of
15 minutes. Three small monthly views are also available, with days containing
items marked.

Certain items may be prioritized, and are then displayed in a bright color to
stand out.

WWW: http://trac-hacks.org/wiki/CalendarPlugin