What is Dbus?
"D-BUS is an interprocess communication (IPC) system, providing a simple yet powerful mechanism allowing applications to talk to one another, communicate information and request services. D-BUS was designed from scratch to fulfill the needs of a modern Linux system. D-BUS' initial goal is to be a replacement for CORBA and DCOP, the remote object systems used in GNOME and KDE, respectively. Ideally, D-BUS can become a unified and agnostic IPC mechanism used by both desktops, satisfying their needs and ushering in new features." (Article on Dbus)
To emerge Dbus, run the following command:
# emerge dbus