gistfile1.aw

// Better yet, sue the language as defined in the entity. $entity->language?

foreach ($GLOBALS['user']->field_product_brand[LANGUAGE_NONE] as $term) {
  if ($entity->field_product_brand[LANGUAGE_NONE][0]['tid'] == $term['tid'])
    return $term['tid'];
  }
}
return NULL;

global $user;
$account = user_load($user->uid);
$entity = node_load($view->args[0]);
foreach ($account->field_product_brand[LANGUAGE_NONE] as $term) {
if ($entity->field_product_brand[LANGUAGE_NONE][0]['tid'] == $term['tid'])
return $term['tid'];
}
}
return NULL;

global $user;
$account = user_load($user->uid);
$entity = node_load(arg(1));
foreach ($account->field_product_brand[LANGUAGE_NONE] as $term) {
if ($entity->field_product_brand[LANGUAGE_NONE][0]['tid'] == $term['tid'])
return $term['tid'];
}
}
return NULL;