We've looked at a few powerline and WiFi products over the last few months. If you can't lay CAT5 cable for whatever reason, or your WiFi signal dips in certain rooms, then they are definitely worth considering. However, the recent Edimax EW-7438RPN WiFi extender relies on some sort of WiFi signal existing, which it then rebroadcasts, hopefully boosting the signal, while a standard powerline adaptor such as ZyXEL's PLA4211, only offers a single Ethernet connection.
ZxXel's PLA4231 is a combination of both, offering a 500mbps powerline adaptor and wireless access point in a single unit. Rather than relying on a weak signal from your router and the rebroadcasting it, the ZyXEL PLA4231 taps into your existing 500mbps powerline network, and dishes out a wireless signal from wherever you plug it in. In addition, it has two Ethernet ports, so could connect your PC and a NAS or media streamer to your network at the same time, while also dishing out a wireless signal for your laptop or tablet to use.
