[rich! @ etiviti]

correct, have a look at the function/filter bp_get_the_topic_last_poster_name (in bp-forums.templatetags.php)

return apply_filters( ‘bp_get_the_topic_last_poster_name’, ‘‘ . $forum_template->topic->topic_last_poster_nicename . ‘‘ );

*edit – annoying we can’t post code here…