<?php
/*
Plugin Name: Dofollow Trackbacks
Plugin URI: http://www.turkhitbox.com/wordpress-seo/dofollow-trackbacks-plugin.html
Description: Dofollow Trackbacks plugin removes the rel="nofollow" attribute in Approved trackback links to share some link love!
Author: Turk Hit Box
Version: 1.0
Author URI: http://www.turkhitbox.com
*/

class trackback_dofollow
{
    function trackback_dofollow()
    {
    remove_filter('pre_comment_content', 'wp_rel_nofollow', 15);
    add_filter('comment_text', array(&$this, 'nofollow_delete'), 16);
    add_filter('get_comment_author_link', array(&$this, 'nofollow_delete'), 16);
    }

    function nofollow_delete($text)
    {
        global $comment;
        apply_filters('get_comment_type', $comment->comment_type);
        
        if ($comment->comment_approved == '1' && ( $comment->comment_type == 'pingback' || $comment->comment_type == 'trackback' ) )
        {
        $text = preg_replace("/(<a [^>]*( |\t|\n)rel=)('|\")(([^\3]*( [^ \3]*)*) )?nofollow/", "$1$3$5", $text);
        $text = preg_replace("/(<a [^>]*)( |\t|\n)rel=(''|\"\")([^>]*>)/", "$1$4", $text);
        return $text;
        }
        else
        {
        return $text;
        }
    }
} 


$trackback_dofollow =& new trackback_dofollow();
?>