wp3 custom post types rss

Use this to include post types to your feed:

function myfeed_request($qv) {
   if (isset($qv['feed']))
   $qv['post_type'] = get_post_types();
   return $qv;
}
add_filter('request', 'myfeed_request');

Just add it to your functions.php. This should help.

Source.