I recently stumbled upon the linksys plk200, it's a linksys product that allows you to run ethernet signal over your homes electrical network.
It costs about $130 for the base unit and a remote. A second remote is about $65 (the PLE200).
The idea is that you can plug wired ethernet devices into the remotes and they connect back into your network (and your router) through the base unit.
They claim you'll have up to 200 MB/s over an encrypted connection - which they offer due to potential sharing of electrical service, such as apartment buildings, etc....
The alternative is to wire ethernet for $1500 for the entire house. I would certainly have all the rooms connected, but I'd rather conserve the cash right now.
I'll update the blog on how it performs. It should arrive late this week.