Qiita が頑張っているので僕も頑張ろうとおもいました。

まずは log.sqlite とかに DB つくりますよ。

install.sql

CREATE TABLE IF NOT EXISTS log (
  current TEXT,
  push TEXT,
  created_at DATETIME
);

で、こんなスクリプトを cron とかで動かしますよ。
勢いで書いたから美しくないけど、許してください。

fbhealth.php

<?php
require_once 'Net/Socket/Tiarra.php';

$api_uri       = 'http://www.facebook.com/feeds/api_status.php';
$db            = __DIR__ . '/log.sqlite';
$pdo           = new PDO("sqlite:$db");
$tiarra_socket = 'riaf';
$irc_channel   = '#nequal@freenode';

$last_row = $pdo->query('SELECT * FROM log ORDER BY created_at DESC')->fetch(PDO::FETCH_ASSOC);

if ($last_row) {
    $last = array(
        'current'    => json_decode($last_row['current'], true),
        'push'       => json_decode($last_row['push'], true),
        'created_at' => new DateTime($last_row['created_at']),
    );
} else {
    $last = null;
}

$now = new DateTime;
$response = json_decode(file_get_contents($api_uri), true);

try {
    if (!isset($response['current'])) {
        throw new Exception('`current` is not found');
    }

    if (!isset($response['push'])) {
        throw new Exception('`push` is not found');
    }

    if ($last) {
        if ($last['current']['health'] != $response['current']['health']) {
            $tiarra = new Net_Socket_Tiarra($tiarra_socket);
            $tiarra->message($irc_channel, sprintf('10Facebook Status: %s (%s)', $response['current']['subject'], $response['current']['health']));
        }
    }

    if (is_null($last) || $last['current']['health'] != $response['current']['health'] || $last['push']['id'] != $response['push']['id']) {
        $insert = $pdo->prepare('INSERT INTO `log` (current, push, created_at) VALUES (:current, :push, :created_at);');
        $insert->execute(array(
            'current'    => json_encode($response['current']),
            'push'       => json_encode($response['push']),
            'created_at' => $now->format('Y-m-d H:i:s'),
        ));
    }
} catch (Exception $e) {
    echo $e->getMessage(), PHP_EOL;
}

Net_Socket_Tiarra が必要なので、入ってない人は

pear channel-discover openpear.org
pear install Net_Socket_Tiarra

とかで入ると思うよ！