DatePickerFragment.cs

  public class DatePickerFragment : DialogFragment, DatePickerDialog.IOnDateSetListener
  {
      public static readonly string TAG = "X:" + typeof(DatePickerFragment).Name.ToUpper();

      Action<DateTime> _dateSelectedHandler = delegate { };

      public DatePickerFragment(Action<DateTime> onDateSelected)
      {
          _dateSelectedHandler = onDateSelected;
      }

      public override Dialog OnCreateDialog(Bundle savedInstanceState)
      {
          DateTime now = DateTime.Now;
          return new DatePickerDialog(Activity, 
              this,
              now.Year,
              now.Month,
              now.Day);
      }

      public void OnDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth)
      {
          DateTime selectedDate = new DateTime(year, monthOfYear + 1, dayOfMonth);
          _dateSelectedHandler(selectedDate);
      }
  }