In lieu of answering this question here, I have made a new Meta-Guide.com webpage on “Dialog Systems in Smart Home Automation & Domotics (Domestic Robotics)” . This webpage was created by extracting all relevant references from my four years of tweets as well as from my Meta Guide website itself.
Although not open source, I imagine that the new Microsoft HomeOS  could be used with the Kinect for Windows , which has speech capabilities. (See also Microsoft Robotics Developer Studio microsoft.com/robotics ..)
I can add that Steve Prior  is a good person to ask about dialog systems in smart homes in general, and about his “Geekster Smarthome”  in particular.