Derick Rethans has announced the first official release of his D-Bus extension that makes it possible for PHP applications (and ones built in other languages) to interact directly with each other.

A few days ago I made the first beta release of the D-Bus extension that I have been working on for a while. D-Bus is a message bus system, a simple way for applications to talk to one another. I started working on this because my cellphone. [...] However, many other applications on the Linux desktop speak D-Bus. This includes system services such as the notification daemon, the screen saver and hardware plug-in detection as well as desktop applications such as Pidgin and Empathy.

You can find out more about the extension on its PECL page or check out Derick's presentation on the subject (as presented at the 2010 PHP London conference).