I was all excited when I found Insteon products made by Smarthome. It is basically X-10 improved. It is a powerline system that has two way communication (and other technical improvement). What that means is that when a controller sends a command to a device, it will make sure that the device got it, and you can also find out about the state of each device (lamps, etc). It also has a very nicely priced keypad that you can mount in standard switch boxes. So, what's wrong with it? In short, it will not work with 3 phase electric systems. Most commercial grade building uses 3 phase systems. Our loft building is one. So it just won't work well.
If you have a house, I think this system is great. But for me, we have to go back to either Z-Wave which is radio based, new, and have a very poor and ugly selection of controllers and devices, or Lutron RadioRA. Stay tune.