--- date_api.module	2008-09-07 23:02:04.000000000 +0200
+++ date_api.module	2008-09-14 20:00:37.000000000 +0200
@@ -92,10 +92,14 @@ function date_month_names_untranslated()
 function date_month_names_translated() {
   static $month_names;
   if (empty($month_names)) {
-    $month_names = array(1 => t('January'), 2 => t('February'), 3 => t('March'),
-      4 => t('April'), 5 => t('May'), 6 => t('June'), 7 => t('July'),
-      8 => t('August'), 9 => t('September'), 10 => t('October'),
-      11 => t('November'), 12 => t('December'));
+    $month_names = array(1 => 'January', 2 => 'February', 3 => 'March',
+      4 => 'April', 5 => 'May', 6 => 'June', 7 => 'July',
+      8 => 'August', 9 => 'September', 10 => 'October',
+      11 => 'November', 12 => 'December');
+    // See format_date() for an explanation of why !long-month-name is necessary
+    foreach ($month_names as $number => $english) {
+      $month_names[$number] = trim(t('!long-month-name '. $english, array('!long-month-name' => '')));
+    }
   }
   return $month_names;
 }