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If you add this code into a file called functions.php and put it into your theme folder, it will show the active names in the topic (if there is more than one person) It uses one extra query but it will also will work on 0.9

add_action('topicmeta','voices_named');

function voices_named() {

global $bbdb, $topic;

$names=$bbdb->get_col("SELECT DISTINCT user_login FROM $bbdb->posts LEFT JOIN $bbdb->users ON poster_id=ID WHERE topic_id=$topic->topic_id AND post_status=0");

$count=count($names);

if ($count>1) {echo "<li>$count members active on this topic: ".implode(", ",$names)."</li>";}

}