• Extensible Messaging and Presence Protocol (XMPP)

XMPP on the wen with PHP :

• Get real time system & server load notification on any IM using PHP and XMPP
• Build a web-based notification tool with XMPP

Listing on www.xmpp.org : Servers, Clients and libraries

http://code.google.com/p/xmpphp

XMPPHP is the successor to Class.Jabber.PHP that I've been promising for years. Taking advantage of PHP5, I believe it to be an elegant solution with a direct approach.

Some of the features include:

• Connect to any XMPP 1.0 server (Google Talk, LJ Talk, jabber.org, etc)
• Supports TLS encryption
• Several XML processing approaches and supported styles (process indefinitely, processUntil an event, processTime for a number of seconds), waiting on events or map them, etc.