function get_redirect_url($url){
        $redirect_url = null; 
     
        $url_parts = @parse_url($url);
        if (!$url_parts) return false;
        if (!isset($url_parts['host'])) return false; //can't process relative URLs
        if (!isset($url_parts['path'])) $url_parts['path'] = '/';
     
        $sock = fsockopen($url_parts['host'], (isset($url_parts['port']) ? (int)$url_parts['port'] : 80), $errno, $errstr, 30);
        if (!$sock) return false;
     
        $request = "HEAD " . $url_parts['path'] . (isset($url_parts['query']) ? '?'.$url_parts['query'] : '') . " HTTP/1.1\r\n"; 
        $request .= 'Host: ' . $url_parts['host'] . "\r\n"; 
        $request .= "Connection: Close\r\n\r\n"; 
        fwrite($sock, $request);
        $response = '';
        while(!feof($sock)) $response .= fread($sock, 8192);
        fclose($sock);
     
        if (preg_match('/^Location: (.+?)$/m', $response, $matches)){
            if ( substr($matches[1], 0, 1) == "/" )
                return $url_parts['scheme'] . "://" . $url_parts['host'] . trim($matches[1]);
            else
                return trim($matches[1]);
     
        } else {
            return false;
        }
     
    }

Ben bu fonksiyonu kullanıyorum. php.net den bulmuştum galiba.

$yeni_url = get_redirect_url($url);

şeklinde kullanabilirsin.