html5 input types in wordpress w/ required attribute

copy_to_functions.php

<?php
/*
 Plugin Name: html5 input-types
 Plugin URI: http://notizblog.org/
 Description: Adds the new HTML5 input-types to WordPress' default forms
 Version: 0.1
 Author: pfefferle
 Author URI: http://notizblog.org/
 */

add_filter("comment_form_default_fields", "change_comment_input_types");

function change_comment_input_types($fields) {
  $fields['email'] = preg_replace('/"text"/', '"email" required', $fields['email']);
  $fields['url'] = preg_replace('/"text"/', '"url" required', $fields['url']);

  return $fields;
}

add_filter("get_search_form", "change_search_form_input_types");

function change_search_form_input_types($form) {
  return preg_replace('/"text"/', '"search"', $form);
}
?>