Will a similar feature be available for Ardour in the future? Could also be useful on the Mixbus side.
netJack lets you connect audio to other computers over the network:
And QmidiNet/QmidiCtl might be what you need for MIDI over the network:
EDIT: And I just remembered zita-njbridge. If I recall it right, Fons Adriansen use this for transportin audio from the concert hall to another room in a concert hall venue.