I've been using it (disclaimer: I've even been hacking on it. ;-)) The standalone Guix-based distribution uses dmd as its init system.

The way it is used, dmd itself takes care exclusively of keeping services running. Services themselves are "translated" to for dmd's configuration file from their higher-level definition (see http://www.gnu.org/software/guix/manual/html_node/Defining-S... ).

The nice thing is that service actions are written in Scheme so they can do anything. For instance, 'static-networking-service' at http://git.savannah.gnu.org/cgit/guix.git/tree/gnu/services/... uses directly the right ioctls to set up the network; so does 'file-system-service' at http://git.savannah.gnu.org/cgit/guix.git/tree/gnu/services/... and so on.