Do we hear the sound of another shoe falling? A couple of weeks ago we wrote about the worries of privacy advocates that the "free" muni-WiFi which large companies now offer municipalities is anything but. It may be the case that consumers will not have to pay cash for the Internet connection being offered, but pay they will, in the form of loss of privacy and being bombarded by ads everywhere they go.

As details of 's plans for San Francisco emerge, privacy worries become more concrete. Privacy advocates say that 's commercial voraciousness reveals a more sinister aspect of its project. said it would use its search engine to track users' locations. may do it so it can tailor advertisements to individual users based on their location: As users walk down the street while on the phone or are sitting in a coffee shop, will send to their PDAs or laptops marketing messages from businesses in the neighborhood in which the users happen to be. If a user happens to be in Union Square, he may see an advertisement for Macy's; if the user uses her laptop near Fisherman's Wharf, she may see an ad for a seafood restaurant (and if users happen to be walking anywhere near AT&T Park, they may see advertising for steroids and other performance-enhancing drugs).

said its technology would allow it to track users' whereabouts to within a few hundred feet. The company also said it would retain the data for up to 180 days before deleting it, as part of an effort to "maintain the WiFi network and deliver the best possible service." Privacy advocates fear the information could be used by government officials to place users under surveillance. Kurt Opsahl, staff attorney for the Electronic Frontier Foundation, a privacy watchdog group, said, "The greatest concern is that once you have that treasure trove of information, will people start to come looking for it?"

What privacy advocates find especially irksome is 's requirement that users log on with a account before accessing the free WiFi. Signing in would make it possible for the company to track Internet use and location to specific individuals. Fears about information collected and retained by are not without foundation. The Justice Department recently tried to make divulge the search records of thousands of its users. The government wanted the information so it could give teeth to a law intended to protect children from Internet pornography. prevailed in the subsequent court battle, but legal experts say the company could have avoided the problem by not keeping user search records.

Privacy advocates have asked to drop the sign-in requirement, arguing that there should be some form of anonymous service so that users can access the Internet "without fear of government or commercial surveillance and intrusion." They have also sent two letters to City Hall to lobby their case.

For more on 's plans for San Francisco:
- see Verne Kopytoff's SFGate.com report
- and Glenn Fleishman's discussion
For more on the -EarthLink winning bid:
- see this arstechnica report 

BACKGROUND: Last Wednesday San Francisco selected and its partner EarthLink to build the city's WiFi network. The network would allow virtually everyone within the city limits to get online without having to plug a cable into their computers for a connection. The parties must still agree on a contract and seek approval from the Board of Supervisors before the network can be installed by year's end, if all goes as expected. will offer the free portion of the WiFi service, which will be supported by online advertising. EarthLink will offer a subscription version that comes with a faster connection. highlighted the user tracking capability in its bid, saying that matching advertising with users based on their location is a good opportunity for small businesses, for which traditional advertising may be too expensive.

PLUS: WiFi will be used more and more not only to track people, but to track assets. In-Stat reports that WiFi is increasingly being used in location tracking applications, and that WiFi asset tags will reach almost 2 million shipments in 2010. The WiFi location tracking market is still nascent, and many highly changeable factors will decide how fast it grows over the next few years, according to the market research firm. WiFi tags are utilized in WiFi Real-Time Location Systems (RTLS), which use WiFi APs to locate devices with external WiFi tags or devices with embedded WiFi. So far, Wi-Fi RTLS has gained the most traction in healthcare. Vendors offering pure WiFi RTLS include Ekahau and PanGo Networks. AeroScout and WhereNet offer more complex RTLS systems. According to In-Stat, expectations are high for WiFi tag chip sets from the likes of G2 Microsystems. In-Stat added that with prices of WiFi tags at approximately $60, the market could get a big push with lower-priced tags. Cisco has partnered with many of the WiFi RTLS vendors, viewing location tracking as another valuable application that can be supported by WiFi infrastructure such as data and voice. Trapeze Networks and Aruba have also begun to stake their ground in this space. Report

ALSO: San Francisco police say cafés offering wireless Internet access have become fertile grounds for robbers making off with pricey laptop computers. Article