This is a pretty big deal.

“A quarter of a million people traverse Market Street every day, from all walks of life,” Mayor Ed Lee said of the new Wi-Fi service. “Now they can access information, find out when their next bus is coming, or peruse local job listings, all for free. This is a significant first step in my vision of connectivity for our city.”

If San Francisco somehow achieves its goals of free wi-fi for the entire city, cable and phone companies that serve the city will no doubt take a huge hit. I suspect that the rate of cord-cutting (people who drop cable and get the majority of their media-related services from the net) will increase dramatically. Cell phone data plans will become unnecessary. Free alternatives to for-pay cell and land-line phone, TV, and, of course, internet will be available.

I can only imagine the gnashing of teeth going on inside Comcast headquarters as they read this news.