If your house has good quality electrical wiring, Homeplug can be a revelation, allowing you to move data at high speed around your home, using nothing more than your mains power sockets and a couple of adaptors. The only problem we've encountered has been transferring 1080p video, which is a little too demanding. Now Solwise has introduced 1,000Mbps adaptors, which aim to increase the possible speeds dramatically.
As with previous iterations, you won't achieve the full speed written on the plug, and 1,000Mbps is certainly fanciful. What you should expect to see are speeds that are roughly equivalent to a 100Mbps Ethernet network. And that means 1080p video should be a distinct possibility.
The biggest hurdle to leap with Homeplug is the quality of your house wiring. When Crave lived in a swanky new-build flat, the speeds were blistering fast. Now we've moved to a Victorian terrace (we all sleep in one bed, like in Charlie and the Chocolate Factory), things are slightly less peachy. But even so, the plugs still work and will happily transfer data on older wiring -- just don't expect full speed.
If you already have the older 200Mbps Homeplugs, these newer ones will work with that hardware, but you'll only see the slower speeds. If you're starting from scratch, you should see top-notch transfer speeds out of the box.
If you're worried about people plugging in a Homeplug of their own, and snooping on your network traffic, don't be. These little babies are encrypted, and outside your home, the signals are blocked by your mains consumer unit, which in turn prevents your neighbours using your Internet connection.
Solwise sells the PL-1000M in packs of two for £87.70 or individually for £44.66 -- although the latter option is currently not in stock. If you're in a network-related bind, and you can't be bothered to employ the A-Team, these are going to be a big help.