P4 Monitor is a script that matches Perforce's log output and ps information and displays it in XML format.
This should allow people to easily write frontends to show the data in a nice, clean format. It also allows you to pipe the data over a network port for a listener on another machine.
P4 Listener is a simple script that takes the output of P4 Monitor and formats it into a webpage. This allows you to do the monitoring on the Perforce server, but have the users hit another web server to view the data, easing the load on the Perforce server.