Google + free + Wi-Fi = You guessed it.

So why exactly is Google going to provide muni broadband to San Francisco? The better to serve you (ads), says the Financial Times.

Google aims to be able to track its users to within 100-200 feet of their location through new wireless networks in order to serve them with relevant advertising from local businesses.

Google and partner EarthLink just won approval from the City of San Francisco to provide free broadband Wi-Fi across the city, part of Mayor Gavin Newsom's commitment to muni broadband. Earthlink would provide higher-speed service for a free. It seems that Google's Wi-Fi would allow the company to pinpoint users by location and provide more specialized services and advertising. For instance, Google Maps could give you directions from your current location, without your having to type your starting location. And, of course, Google could place ads based on your location, not just based on the content of your current page.

Google says users linking up with wi-fi transmitters placed around cities can be located to within a couple of blocks. This would open up a new level of advertising opportunities for the company, allowing it to serve tightly focused ads on its web pages from small businesses in the immediate area.

The bid to blanket-cover San Francisco with cheap internet access is part of a broader move towards municipal wireless networks by big US cities.