No it doesn't work like that, the datepicker fills the value of the form field via javascript with the format yyyy-mm-dd
when using php to fill the form value I always give it the value of time() to create the date from as this will be the "correct" date/time rather than the server time which can be incorrect this is especially true when hosting uk sites on a us server
I use this in conjunction with this code in my application file
php:
/*
Set Timezone
----------------------------------------------------------
*/
ini_set('date.timezone', 'Europe/London');
to set the correct time zone
So <?php echo date('Y-m-d', time()); ?> wil populate the hidden form field with a date formatted like yyyy-mm-dd
