I started to go down this path a while ago and picked up a Logitech Squeezebox Duet. Lots of options of controlling the audio from many different sources, but it doesn't address the actual wiring and speaker placement throughout the house... just the music source itself. Still, I thought this was a good starting point!
Here is some info, although you can find better deals on Amazon, eBay and other sources.
http://www.logitech.com/index.cfm/sp.../3817&cl=US,EN