Edit in JSFiddle

$(document).ready(function() {
    var SelectedDates = {};
    SelectedDates[new Date('04/05/2012')] = new Date('04/05/2012');
    SelectedDates[new Date('05/04/2012')] = new Date('05/04/2012');
    SelectedDates[new Date('06/06/2012')] = new Date('06/06/2012');
    
    var SeletedText = {};
    SeletedText[new Date('04/05/2012')] = 'Holiday1';
    SeletedText[new Date('05/04/2012')] = 'Holiday2';
    SeletedText[new Date('06/06/2012')] = 'Holiday3';    

    $('#txtDate').datepicker({
        beforeShowDay: function(date) {
            var Highlight = SelectedDates[date];
            var HighlighText = SeletedText[date]; 
            if (Highlight) {
                return [true, "Highlighted", HighlighText];
            }
            else {
                return [true, '', ''];
            }
        }
    });
});

<input type='text' id='txtDate' />