These changes to Datepicker caused my dates of '2010-02-02' to display as '2'. The correct value was a string in $element['#value'], yet isset($element['#value']['value']) was TRUE, so I think this is a case of PHP strings behaving as arrays?  In any case, changing line 54 to is_array($element['#value']) instead of is_array($element) fixed it for me.