Im working on a new project now, ive been brains storming ideas for this for years, and ive just now able to get parts for it all. I already ordered an ARM9 board
(Specifically :: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=110670930230&ssPageName=STRK:MEWNX:IT#ht_2937wt_1139 )
and it has serial output ports on it that i will be putting into an Arduino mega board to control a sub system. My original idea was to use relays to control all items outside of the panel, but then i realized that there will be a hell of alot of wiring. So im contemplating PLC, or Power Line Communications. I touched on it briefly in Technical school, but never really got into it. I under stand the basic concept of modifying the frequency of the main power lines in my home and adding a signal in the trough of the wave. Then id have to build a filter on the line somewhere and pull the signal off. My question is, is this possible to do with arduino? Im not against building my own circuits (who is??) but id love to have a schematic to go off of. Essentially i want to built a power plug (110V) with an Arduino nano, an interface to the mains power, and a relay to turn off and on the receptical. then once ive mastered the art 
ill move on to dimmers and what now.