root/tags/release-1.0/wp-commentsrss2.php

<?php 

if (empty($wp)) {
    require_once('wp-config.php');
    wp('feed=rss2&withcomments=1');
}

header('Content-type: text/xml;charset=' . get_option('blog_charset'), true);

echo '<?xml version="1.0" encoding="'.get_option('blog_charset').'"?'.'>'; 
?>
<!-- generator="wordpress/<?php echo $wp_version ?>" -->
<rss version="2.0" 
    xmlns:content="http://purl.org/rss/1.0/modules/content/">
<channel>
<?php
$i = 0;
if (have_posts()) :
  while (have_posts()) : the_post();
    if ($i < 1) {
        $i++;
?>
    <title><?php if (is_single() || is_page() ) { printf(__('Comments on: %s'), get_the_title_rss()); } else { printf(__('Comments for %s'), get_bloginfo_rss("name")); } ?></title>
    <link><?php (is_single()) ? permalink_single_rss() : bloginfo_rss("url") ?></link>
    <description><?php bloginfo_rss("description") ?></description>
    <pubDate><?php echo gmdate('r'); ?></pubDate>
    <generator>http://wordpress.org/?v=<?php echo $wp_version ?></generator>

<?php 
        if (is_single() || is_page()) {
            $comments = $wpdb->get_results("SELECT comment_ID, comment_author, comment_author_email, 
            comment_author_url, comment_date, comment_date_gmt, comment_content, comment_post_ID, 
            $wpdb->posts.ID, $wpdb->posts.post_password FROM $wpdb->comments 
            LEFT JOIN $wpdb->posts ON comment_post_id = id WHERE comment_post_ID = '" . get_the_ID() . "' 
            AND $wpdb->comments.comment_approved = '1' AND $wpdb->posts.post_status = 'publish' 
            AND post_date_gmt < '" . gmdate("Y-m-d H:i:59") . "' 
            ORDER BY comment_date_gmt DESC LIMIT " . get_option('posts_per_rss') );
        } else { // if no post id passed in, we'll just ue the last 10 comments.
            $comments = $wpdb->get_results("SELECT comment_ID, comment_author, comment_author_email, 
            comment_author_url, comment_date, comment_date_gmt, comment_content, comment_post_ID, 
            $wpdb->posts.ID, $wpdb->posts.post_password FROM $wpdb->comments 
            LEFT JOIN $wpdb->posts ON comment_post_id = id WHERE $wpdb->posts.post_status = 'publish' 
            AND $wpdb->comments.comment_approved = '1' AND post_date_gmt < '" . gmdate("Y-m-d H:i:s") . "'  
            ORDER BY comment_date_gmt DESC LIMIT " . get_option('posts_per_rss') );
        }
    // this line is WordPress' motor, do not delete it.
        if ($comments) {
            foreach ($comments as $comment) {
                $GLOBALS['comment'] =& $comment;
                // Some plugins may need to know the metadata
                // associated with this comment's post:
                get_post_custom($comment->comment_post_ID);
?>
    <item>
        <title><?php if ( ! (is_single() || is_page()) ) {
            $title = get_the_title($comment->comment_post_ID);
            $title = apply_filters('the_title', $title);
            $title = apply_filters('the_title_rss', $title);
            printf(__('Comment on %1$s by %2$s'), $title, get_comment_author_rss());
        } else {
            printf(__('by: %s'), get_comment_author_rss());
        } ?></title>
        <link><?php comment_link() ?></link>
        <pubDate><?php echo mysql2date('D, d M Y H:i:s +0000', get_comment_time('Y-m-d H:i:s', true), false); ?></pubDate>
        <guid><?php comment_link() ?></guid>
            <?php 
            if (!empty($comment->post_password) && $_COOKIE['wp-postpass'] != $comment->post_password) {
            ?>
        <description><?php _e('Protected Comments: Please enter your password to view comments.'); ?></description>
        <content:encoded><![CDATA[<?php echo get_the_password_form() ?>]]></content:encoded>
            <?php
            } else {
            ?>
        <description><?php comment_text_rss() ?></description>
        <content:encoded><![CDATA[<?php comment_text() ?>]]></content:encoded>
            <?php 
            } // close check for password 
            ?>
    </item>
<?php 
            } 
        }
    }
endwhile; endif;
?>
</channel>
</rss>