I was looking at getting the house wired for Ethernet. I do not have any major requirements at the moment, I do not intend to stream HDMI over the network :). About as bad as we get is streaming from the media centre to an extender (XBox 360) which is around 1.5Mb for a HD stream.
I found out about MoCA and did some research, from what I could tell it would meet all my requirements, better still I did not need to get anything re-wried as we have points at every place in the house that I wanted a network outloet.
I picked up 2 of them which gave me 4 points, I now have a nice stable network (Wireless N was spotty when streaming from my Media Centre to the XBox 360) which allows me to stream and move my server to a out of the way location in the house.
It does not have the same capabilities as a fully wired Cat6 network but for my needs it works a treat!