BuddyPress.org

And for the activity comments:
add_filter(‘bp_activity_comment_date_recorded’, ‘bp_activity_comment_date_recorded_newformat’, 10, 2);
function bp_activity_comment_date_recorded_newformat( $date_recorded ) {
global $activities_template;

$timestamp_now = time();
$timestamp_comment_date_recorded = strtotime( $activities_template->activity->current_comment->date_recorded );

if (abs($timestamp_now – $timestamp_comment_date_recorded) > 60 * 60 * 24 ) {

$date_recorded = date_i18n( “j F Y H:i”, $timestamp_comment_date_recorded );
}
return $date_recorded;
}