You can use BeforeCellRender event handler to highlight today.

JavaScript

dp.onBeforeCellRender = function(args) {
  if (args.cell.start.getDatePart().getTime() === new DayPilot.Date().getDatePart().getTime()) {
    args.cell.backColor = "silver";
  }
};

ASP.NET WebForms

 
protected void DayPilotCalendar1_BeforeCellRender(object sender, BeforeCellRenderEventArgs e)
{
  if (e.Start.Date == DateTime.Today) {
    e.BackgroundColor = "silver";
  }
}

ASP.NET MVC

 
protected override void OnBeforeCellRender(BeforeCellRenderArgs e)
{
  if (e.Start.Date == DateTime.Today) {
    e.BackgroundColor = "silver";
  }
}