Overheard: How will power-line broadband work?

International Business Machines Corp. said it has been hired to work with rural electricity cooperatives to provide high-speed Internet service over power lines. The project is a sign that using the electricity grid for communication — a technology utilities have long been interested in — has finally matured. William M. Bulkeley, IBM Hired to Develop Power-Line Broadband

The system works by using standard power lines to carry a radio-frequency signal in the magnetic field that surrounds the wires. The signal is continuously amplified by low-priced repeater boxes clamped to the lines. When an electricity customer signs up for broadband services, the supplier mails out a special modem that is plugged into the wall outlet where the computer is plugged in.

UPDATE 8-03-09: IBM IBM and an ISP called International Broadband Electric Communications announced they have begun to establish broadband over power line (BPL) networks for nearly 200,000 rural customers served by 7 electrical cooperatives in Alabama, Indiana, Michigan and Virginia.