I am using JQuery ui with datepicker and when a user tabs on to a field, they appropriately get the calendar pop up.
Similar to Jimmy's approach, but this sets the focus to the calendar icon (assuming your calender uses an icon), I found this way more appropriate when I had multiple date pickers next to each other.
Set the date default options so that they set focus to the icon when the calendar popup closes:
$(".date").datepicker({
onClose: function() {
$(this).next('a').focus();
}
});
Add a tag to the calendar icon so that it's focusable:
$(".date").each(function() {
$($(this).next('img')).wrap($("").attr("href","#"));
});