Today, most people (at developed countries) carries some Bluetooth capable cell phone or, looking at the current supply at shops, they will very soon. Bluetooth is a wonderful technology that joins power efficiency with easiness, making things like file sharing, wireless hands free and so a child's game. Of course, Bluetooth is not an exclusive property of the handheld world, and it's easy to find USB Bluetooth devices in the 15€/10$ range, and many new computers include it by default.

In addition, Bluetooth management has been developed in the Linux world for some years, now we have the BlueZ stack integrated in 2.4 and 2.6 kernels providing a library to manipulate Bluetooth devices and a D-Bus interface with the same purpose. Also, KDE has gone it's way and has the KDEBluetooth project, which provides a DCOP interface to the underlying BlueZ DBus interfaces, but has one little issue, is not KDE4 ready. The first part of this proposal is to solve that problem.

All this plots an scenario where a user arrival/leaving can be easily identified from Linux using few different ways. What if your computer pauses the music you are listening on Amarok, locks the screen and mutes the audio when you leave, and also unlock the screen, restart playing your music and opens your favorite mail program and a browser with your favorite tabs when you get back to range. This is a feature that has already been included in OSX through the Proximity application, or even on Linux with the command line tool bluemon, so this proposal includes creating a similar application called Bluetooth Presence Manager, BtPM, using KDE4, on top of the previous Bluetooth support works.