First, there was X10. There was appetite for something better. There were several candidate replacements, including:

* UPB - Universal Powerline Bus (powerline)

* Insteon (powerline + wireless)

* Z-Wave (wireless)

* Zigbee (wireless)

Of these, Zigbee seems to be in the best position these days.

Z-Wave is/was a closed system - you had to get compatibility testing/certification in order to sell products using the tech. It's fairly lightweight, reliable, and well respected by users.