If you are using Debian or Ubuntu, and installed the Gnome system by default. Your system probably already has Gnome Volume Manager.
The Gnome Volume Manger is a daemon which listens the hardware events (HAL event), and run the user-configurable commands. Basiclly, it do autorun, automount for the hot-plugged devices. In plain English, it run the Multimedia Player or CD Burning software when you put a CD into the cdrom driver.