VolumeManager is basically a GNustep daemon/tool that uses HAL and DBUS to detect newly attached / removed / mounted / unmounted volumes. What does it do further? Well, a GNUstep application can register itself as DO client at VolumeManager and will get notified about such changes and may also use DO to mount/unmount volumes. Moreover, VolumeManager can be configured such that is automatically mounts new data volumes or that it automatically plays audio CDs or DVDs using GNustep services. In addition to the daemon the package contains a plugin to SystemPreferences to configure VolumeManager and it does contain a menulet for Étoilé's menu server that displays mounted volumes and allows to unmount them.