@GMaq: As far as I know, Qmidinet can also be used to interface to some control surfaces (e.g. Various SSL controllers such as the "Nucleus"
http://www.solidstatelogic.com/music/nucleus whch transmit / receive their MIDI control codes using 'ipMIDI' over ethernet)
Qmidinet was used to interface this controller to Ardour during the development of support for the Nucleus in A3, although I believe Paul has now integrated the ipMIDI layer directly into A3 (interestingly, I think that makes A3 one of the few DAWs to support a controller such as the nucleus 'straight out of the box' without the need for other additional intermediary software / drivers..)