--- modules/optionwidgets/optionwidgets.module	Fri Sep 11 10:00:56 2009
+++ modules/optionwidgets/optionwidgets.module	Tue Jan 25 10:49:01 2011
@@ -410,6 +410,10 @@
       $options = array('' => theme('optionwidgets_none', $field)) + $options;
     }
   }
+  // Add a blank option for required selects
+  if ($field['required'] && in_array($field['widget']['type'], array('optionwidgets_select', 'nodereference_select', 'userreference_select')) && !isset($options[''])) {
+    $options = array('' => '') + $options;
+  }
   return $options;
 }