Products of like this homeplug system have appeared on the market in the last year or two. Technology is rapidly advancing and soon you will be able to get broadband, telephone and cable TV just by plugging a device into any ordinary mains socket outlet. Question is, will we see energy and telecom companies merge?
I still see a problem with security. That device is not using very strong encription and what covers your house also covers every house on your side of the transformer, maybe farther if you are on aerial distribution. There are already lots of hackers driving around looking for wireless access points (War Driving). I prefer not to have my data hanging out for the world to see. I think that dedicated wiring will be with us for a while yet. If the plug in devices get very common, us electricians will likely get a lot of business bringing power wiring up to acceptable data standards.