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, an OpenMoko FreeRunner. This cellphone (or rather, a mobile Linux computing device) implements freesmartphone.org APIs to talk to all the hardware that is available on the device. This includes GSM and SIM card interfaces, but also GPS, Audio and PIM services.
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.
I've given a presentation on the extension at the PHP London conference earlier this year, and will also be speaking on this subject as part of the "PHP Inside" and "PHP on the D-Bus" talks at Tek-X (Chicago, May 18-21), International PHP Conference Spring (Berlin, May 30-June 2) and the Dutch PHP Conference (June 10-12).