Wordpress-pubsubhubbub-subscriber is a project mainly written in PHP, it's free.
Wordpress pubsubhubbub client (subscriber) plugin
blah blah
function email_friends($p1,$p2) {
wp_mail( '[email protected]', 'subject 1', "b1: " . print_r($p1,1) . " b2: " . print_r($p2,1) ); return $p1; }
add_action('push_feed_submitted', 'email_friends',10,2);