[Lynne]

$activeusers is literally just the list of active users. You could just use the template_hook there in search_resultlist. Use the hook location search_start and then try (at the end of your code you stole from forum.php):

$template_hook['search_results_top'] .= $activeusers;

And you'll get a list of active users. You'll have to pretty it up with <div>s and all.