Well, theconceptrevolves around the ideathat the basicshellorinfrastructureshouldprovide the bare necessities: power, networking, management, ahigh-speedbus, cooling, andstorage.
Google has about 900, 000 servers, so Facebook needs 27, 000 additional servers (plus power and networking infrastructure) for no obvious financial return.
Power companies and networking startups have spent years touting a technology called broadband-over-power lines, or BPL. In those systems, the utility sends a data signal across existing wires at a much higher frequency than electricity, so the two signals don't interfere.