Two G.hn powerline adapters arrived this week (at the Rider Research offices for review) from Sigma Designs, which makes G.hn chips. The adapters have an AC outlet built in so the user doesn’t lose a power outlet when they are plugged into the wall. The adapters we received are “reference” units that equipment makers can use as a pattern when developing their own G.hn devices. A few equipment makers, such as Taiwan-based Prime Electronics and Satellitics (PES) with a set-top box, have already announced products with G.hn embedded. That means that once the STB or TV is plugged into the power socket, it’s automatically connected to the home network and to the Net via the home’s powerline. The power cord…