Chat Servers, both publicly available ( gtalk, msn etc) and private locally hosted chat servers, can be used by net connected hardware and systems as a communication channel.
Jabber / XMPP is the open messaging protocol used by most chat systems, and plenty of client software is available.
On the OpenWrt Midge router, space and processing power is at a premium, but using the php chat client xmpphp, getting your hardware to send a message to you phone, pc, or other chat connected system is as simple as this:-
<?php
include("xmpp.php");
$conn = new XMPP('yourchatserver.net', 5222, 'accountname1', 'password',
'xmpphp', 'yourchatserver.net', $printlog=False,
$loglevel=LOGGING_INFO);
$conn->connect();
$conn->processUntil('session_start');
$conn->message('accountname2@yourchatserver.net',
'This is a test message!');
$conn->disconnect();
?>
Although publicly available chat servers can be used, if you are going to have several systems, each one requiring its own account on the chat server, running your own will make things easier to manage.
Using http://www.dyndns.com/, it is possible to get a domain name for your Internet connection.
Forward the standard jabber/xmpp ports on your broadband router to a machine running the Openfire Chat Server and you have your own chat system that you can use to talk to people and hardware connecting via the Internet – you just have to create accounts for them – or allow public registration.