Though perhaps not necessarily helpful for you right now, I've heard of people using Siri (the voice control in the iPhone iOS 5) to control their home automation systems. This is definitely in its infancy, but perhaps people will build a product out of it. I saw a demo on Engadget of a guy controlling his thermostat and it worked really well. Voice control is definitely getting better so I think a valuable voice controlled home automation product is just around the corner.