How can I get the date_popup module to display AM/PM in the time selector?
I remember having a similar issue - I fixed it using a custom module like this, the possible cause was probably that Drupal and jQuery returned different formats...

$GLOBALS['locale'] = $locale = 'fr';

/* [...] */

function x_form_alter(&amp;$form, &amp;$form_state, $form_id){
    // Fix date format in some exposed date filters (cck date)
    $date_format = 'd/m/Y'; /* Should be same as in "sites/all/js/jquery.datepicker/$locale.js" */
    foreach($form as $key =&gt; $value){
        isset($value['value']['#date_format']) &amp;&amp; $form[$key]['value']['#date_format'] = $date_format;
        isset($value['min']['#date_format']) &amp;&amp; $form[$key]['min']['#date_format'] = $date_format;
        isset($value['max']['#date_format']) &amp;&amp; $form[$key]['max']['#date_format'] = $date_format;
    }
}


I guess you can adapt this code to your situation and even better, suggest a cleaner solution.