placement of relays for home automation

I'm hoping to use the Arduino to fully automate my home.

Mostly with Ethernet cabling for switches.

Where to place the relays:

Centralised, 1 or 2 central points so all electrical cabling comes to these points and wired to many relays.

Or separate relays placed at each "switch" point.

To me the centralised seems the better option but many seems to go with de-centralised.

Z Wave and others seems to be de centralised not that I intend to use Z wave.

Any thoughts, ideas, much appreciated.


For some ideas and inspiration, have a look over at
Jon is in the process of a whole-home automation system.

I have watch a lot of Super house TV.

Being Australian is certainly a plus as I live in Oz.

It has some great stuff and ideas.

But start pricing his switches, seems expensive why bother DIY.

The challenge is to do something that is equal to or better than off the shelf at a better price.

This same point was mentioned by others on this or on Freetronics forums but was not really answered.