<?php
function publish_to_hub($post_id)  {

    // we want to notify the hub for every feed
    $feed_urls = array();
    $feed_urls = apply_filters('push_feed_urls', $feed_urls); // <-- a filter to add some more feeds
    $feed_urls[] = get_bloginfo('atom_url');
    $feed_urls[] = get_bloginfo('rss_url');
    $feed_urls[] = get_bloginfo('rdf_url');
    $feed_urls[] = get_bloginfo('rss2_url');

    // remove dups (ie. they all point to feedburner)
    $feed_urls = array_unique($feed_urls);
    // get the list of hubs
    $hub_urls = get_pubsub_endpoints();
    // loop through each hub
    foreach ($hub_urls as $hub_url) {
        $p = new Publisher($hub_url);
        // publish the update to each hub
        if (!$p->publish_update($feed_urls, "http_post_wp")) {
            // TODO: add better error handling here
        }
    }
    return $post_id;
}