I finally ran into a situation where my calendar needed events so I added the functionality tonight. You can currently create events using a Zend_DbTable or a regular array but extending Spiffy_Calendar_Event_Abstract allows you to create events from any source (JSON/Google Calendar come to mind).
$calendar = new Spiffy_Calendar();
// Array using object
$test = new Spiffy_Calendar_Event_Array($calendar);
$test->setData(array(array('title' => 'Array with event')));
$test->setDay(1);
$calendar->createEvent($test);
// Array using type
$calendar->createEvent('array', array(array('title' => 'Array with type')), array('day' => '25'));
// Table using type with date set using date_field and date_format
$calendar->createEvent('table', new Default_Model_DbTable_Event(),
array('date_field' => 'date', 'date_format' => 'YYYY-MM-DD'));
// Table using object with select using current date
$test2 = new Spiffy_Calendar_Event_Table($calendar);
$test2->setData(new Default_Model_DbTable_Event());
$test2->getSelect()->where('id = ?', 2);
$calendar->createEvent($test2);
$this->view->calendar = $calendar;
The above code generates a table that looks like:

SpiffyCalendar with events demonstration
I think SpiffyCalendar is finally starting to come together. More to come!