Ideally I'd like to provide new classes to the body tag such a access-404 or access-denied, but unfortunately I'm not really aware of how to capture these.
I don't mind to identify these pages from the Page Title itself from template_preprocess_page, however it seems that $vars['title'] does not exist in D7? How can I access the page title from within a template_preprocess function?
SOLUTION: Thanks to DeeZone:
In my template.php:
function template_preprocess_html(&$vars){
$status = drupal_get_http_header("status");
switch($status){
case "403 Forbidden":
case "404 Not Found";
$vars['classes_array'][] = 'drupal-page-error';
dsm($vars);
break;
}
}