bluemon 1.4-2.0.1 (i386 binary) in ubuntu feisty

 BlueMon monitors the quality of the link to a Bluetooth device and can start
 or stop programs when the threshold drops below a certain value. This can be
 used to perform actions like locking the terminal when you walk away from it.
 .
 Bluemon uses the DBus system bus to alert other applications to the presence
 of Bluetooth devices. A user binary can then start or stop programs when such
 signals are received.