I live in San Francisco, the city where Wi-Fi access is considered a fundamental right. Seriously, that's what our mayor, Gavin Newsom, said recently.

Of course, in a densely packed city full of badly configured routers, free Wi-Fi is already a reality for many San Franciscans. In my building, anybody can just tap into an unsecured router cleverly named WLAN whenever they get the urge. I already have five wireless networks visible from my home PC, so you'll forgive me if I sometimes mistakenly believe that I'm already living in a world of ubiquitous Wi-Fi.

Still, while Wi-Fi access may not make it onto the Universal Declaration of Human rights anytime soon, the idea of this kind of service being as freely and widely available as street lights or paved roads is pretty compelling.

Just as streetlights made the streets safer and paved roads sped up commerce, it's easy to imagine Wi-Fi bringing all kinds of social benefits to San Francisco - from a more computer-literate population to a city filled with next-generation Web services that change the way we shop and socialise.

In fact, that opportunity may explain why

But what are the true costs? If you look closely, there are more important policy issues surrounding municipal Wi-Fi than the question of whether or not the service will carry popup ads.

As my fellow San Franciscan, Technorati chief executive officer Dave Sifry told me the other day, the more interesting questions include: How do you make sure that the network doesn't get abused? How much bandwidth do you allow? What about authentication? What kind of services do you allow? File sharing? Mail servers? How do you prevent your free network provider from becoming another kind of monopoly?

"If you think too naively about this, you can have a system that's really rife for abuse," Dave told me.

And the Google connection made him a little uneasy too. "It does sort of make you wonder a little bit about how your Web surfing is then being tracked and what are the privacy issues," he said.

Luckily for Dave and me, Philadelphia may already be working some of these issues out ahead of us. It awarded a municipal Wi-Fi contract to EarthLink that will leave about 135 square miles (350 square kilometers) of the city blanketed with 1 Mbit/s Wi-Fi by the end of next year.

Rather than serving up ads, the EarthLink network will charge users US$20 per month for access and offer a reduced rate of $10 a month for low-income households, making this municipal utility seem a little more like water than roads or street lights.

It will be interesting to see how this grand vision develops. The mayor has already warned that he expects lawsuits, presumably from unhappy Internet service providers, and while there hasn't been much debate about the privacy or security concerns, the San Francisco Examiner recently ran two reader letters asking how safe all these Wi-Fi antennas might be. "What sort of radiation will they be emitting?" a reader asked, suggesting that the project be put on hold until the health risks of wireless networking are better understood. "Let's not be in too big a hurry in the name of progress."

This guy obviously doesn't live in my building.