In functions.php:

<?php

add_action('init', 'dgo_connection_types', 100);
add_filter('p2p_connectable_args', 'dgo_connectable_places', 10, 2);

function dgo_connectable_places($args, $context) {
    if ('place' == $args['post_type']) {
        global $wpdb;

        $query = "SELECT $wpdb->p2p.p2p_to AS post_id FROM $wpdb->p2p";

        $result = $wpdb->get_col($query);

        $args['post__not_in'] = $result;
        $args['orderby'] = 'date';
        $args['order'] = 'ASC';
    }
    return $args;
}

function dgo_connection_types() {
    if (!function_exists('p2p_register_connection_type'))
        return;

    global $postplaces;

    $postplaces = p2p_register_connection_type(array(
        'from' => 'post',
        'to' => 'place'
            ));
}
?>

In index.php:

<?php if (have_posts()) : ?>
    <?php
        global $wp_query;
        $postplaces->each_connected($wp_query);
    ?>
    <?php while (have_posts()) : the_post(); ?>
    <?php global $post; ?>
    <?php print_r($post); // $post->connected is not present ?>
    <?php endwhile; ?>
<?php endif; ?>