Here's a copy of something I just posted elsewhere about how old this is.
I posted this in response to another discussion on this issue and felt it should be here too.
About ten years ago I read a magazine article about a group of apartment complexes built in Japan where EVERYTHING in the apartment was computer controlled - they were turned on, off, up, down, and monitored by the computer. You could prepare your evening meal and put it in the oven, program the oven application in the computer with the time heat etc (with a multitude of adjustments), and leave for work; when you arrive home the meal is ready as per what you programmed. Also the air-conditioner turned on at the right time and the apartment is just how you want it. It also included a fridge that kept track of what's in it and prepared your grocery list for you, all you did was confirm it or amend it on the PC and send it off to the store to have it delivered when you get home that night. In some they even had them set to prepare breakfast of a morning, including controlling the toaster and coffee maker.
Now, I see this as much the same as that, except someone has decided they need to put it all out on the Internet, but I fail to see the need to do that. I know if I had a house with all these appliances I'd make damn sure that my Internet access had a router that did NOT allow them access to the Internet at all as I don't want stuff going out unless I've approved it.
Now, as to how this can be useful - think live telemetry on anything you want and using Ethernet or wi-fi or Bluetooth to send and capture the signals.
I can see how useful this would be in a production environment to help with monitoring the production machinery, ad wi-fi or Bluetooth options would reduce the cabling but increase the possibility of EM messing the signal or competitors listening in by parking nearby. With all your production gear hooked up and monitoring via Ethernet in segregated LANs for each line there is benefit. I can also see it being used to provide more remote monitoring in some medical environments. It can also be useful to help with monitoring and managing gardening with computer controlled watering devices etc. Also good for computer controlled access to buildings and rooms can be done by Ethernet instead of lots of dedicated cables. Again, you do NOT want this on the Internet but on a LAN.
Beyond those uses it's more likely just a fancy toy set up.