Hey, I was looking into an article on Slashdot.org about a new pvr box when I saw that they were offering ethernet-over-powerline adapters. I still have a phoneline adapter that will turn any phone jack into 10mbit ethernet, but it isn't really fast enough for streaming video. Apparently Netgear has come out with a powerline router/adapter that will turn any electric outlet in your house into a 200mbit ethernet jack. Up to 16 devices are supported and it costs about around 250usd for the router and 2 adapters (200mbit version) and lower for the 85mbit version. They also have wireless adapters that plug into the wall that are good for 54mbit.

Here is the netgear link, i'm sure dlink or cisco/linksys have competing products.