For anyone looking to extract a network connection from the mains without the "horizontal overhead" of a plug-in adapter, Powerline Wall Sockets sound like a clever idea - apart from the price (Dec 2014 - £79 upwards!).
But there is another snag which had not dawned on me until mentioned by a really helpful chap at Solwise
. If your network locks up, plug-in adapters can be removed and replaced to achieve a reboot, just as other networking elements can be turned off and on again. But your Powerline Wall Socket will have no facility for powering down the Powerline part, leaving you to turn off the whole mains circuit at your fuse box if you want to reboot it!