We have just updated to JQuery 1.5.2.min and JQuery-ui-1.8.11.min and are using the latest datepicker.js files as well (I say files because we are using some of the localize
I've had this same bug for a while and just got around to looking at it tonight. I'm not sure why this bug occurs, but the following is what I've done to eliminate the visual artifact on the screen. Right after you create your datepicker(s), execute the following:
$('#ui-datepicker-div').css('display','none');
Caveat: When I look at the dom generated by Safari and step through the code that creates the datepicker, the code above appears to do nothing to the dom, but it does hide the visual affect on the screen.