Page - specific Datepicker config in jcalendar.tpl
You can set a datepicker's default value in the setDefaultValues() method of the form.  Here is a snippet of code that sets a date to today if none exists, and to a saved date if it does:



    if (empty($data['thank_you_date'])) {
      $defaultValues['thank_you_date'] = date('Y-m-d');
    } else {
      $defaultValues['thank_you_date'] = $data['thank_you_date'];
    }