var disabledDays = ["2011-7-21","2011-7-24","2011-7-27","2011-7-28"];
var date = new Date();
jQuery(document).ready(function() { 
    $( "#dateselector").datepicker({ 
        dateFormat: 'yy-mm-dd',
        beforeShowDay: function(date) {
            var m = date.getMonth(), d = date.getDate(), y = date.getFullYear();
            for (i = 0; i < disabledDays.length; i++) {
                if($.inArray(y + '-' + (m+1) + '-' + d,disabledDays) != -1) {
                    //return [false];
                    return [true, 'ui-state-active', ''];
                }
            }
            return [true];

        }
    });
});