a simple improvement on jqueryUI datepicker to enable the time setting.

datetime_picker.js

$(document).ready(function(){
  date_obj = new Date();
  date_obj_hours = date_obj.getHours();
  date_obj_mins = date_obj.getMinutes();

  if (date_obj_mins < 10) { date_obj_mins = "0" + date_obj_mins; }

  if (date_obj_hours > 11) {
      date_obj_hours = date_obj_hours - 12;
      date_obj_am_pm = " PM";
  } else {
      date_obj_am_pm = " AM";
  }

  date_obj_time = " '"+date_obj_hours+":"+date_obj_mins+date_obj_am_pm+"'";
  
  $('input.date_picker').datepicker({dateFormat: $.datepicker.W3C + date_obj_time});
});