add and register scripts conditionally for IE from the wordpress functions PHP

wp-ie-conditional.php

// add ie conditional html5 shim to header
function add_ie_html5_shim () {
    global $is_IE;
    if ($is_IE)
        wp_register_script ('html5shim', "http://html5shim.googlecode.com/svn/trunk/html5.js");
        wp_enqueue_script ('html5shim');
}
add_action('wp_head', 'add_ie_html5_shim');