SO jQuery Fiddle
Test Fiddle mainly for SO Questions jQuery 1.4.3, UI 1.8.5
HTML
<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.5/themes/ui-lightness/jquery-ui.css">
<p>Date: <input type="hidden" id="datepicker"></p>
JavaScript
$( "#datepicker" ).datepicker({
showOn: "both",
buttonImage: "http://jqueryui.com/demos/datepicker/images/calendar.gif",
buttonImageOnly: true
});