This looks quite promising!!

http://e3d-online.com/Multi-Extrusion/Cyclops

A bit more info here!!
http://hackaday.com/2015/03/25/mrrf-...-stoic-swedes/

Any idea what it would take to get our MF printers using this? I can't imagine how color switching works, since a single nozzle design will require that the machine switch the color it is extruding BEFORE it needs the new color (at precisely the right moment) to flush the exact amount of excess material from the nozzle.