On Wednesday, Google announced that users of version 2.0 of Google Maps for mobile would be able to see their approximate location on the mobile map. Rather than rely strictly on GPS, which is not available in all phones and can drain mobile batteries quickly, Google uses cell tower ID information to calculate the device's location.

The accuracy of the mapping depends to a large degree on how far away the device is from the nearest cell towers. In a quick test in the Burlington, Vermont area yesterday, the "My Location" feature was very accurate on the University of Vermont campus but was off by three blocks in the downtown area.

Truly Anonymous?

According to the Google press release, the "My Location" feature is anonymous: "Google does not gather any personally identifiable information or associate any location data with personally identifiable information as part of the My Location feature." The company also said that anyone who does not want to use the feature can disable it.

But some privacy advocates remain unconvinced. "Google's mobile maps creates an unnecessary privacy risk," Marc Rotenberg, executive director of the Electronic Privacy Information Center, said in an e-mail.

In his view, it is safer and more private for consumers to use a standalone GPS device for location information. "A typical GPS device leaves the user in control of mapping data and search histories are easy to delete," Rotenberg said.

A query to Google for more specific information about its "My Location" feature was unanswered at the time this article was filed, but the company's own "Mobile Privacy Policy" raises more questions than it answers.

Location-Based Ad Revenues?

For instance, to provide mobile information, Google says it might collect a wide variety of personal data: "your device and hardware IDs and device type, the request type, your carrier, your carrier user ID, and the content of your request." However, because Google presumably does not have access to the cellular company's records, it cannot link a given carrier user ID to a specific cellular customer .

But some analysts argue that location-based advertising is the next major revenue stream, and that Google is positioning itself to be at the front of the line. In an interview earlier this week about Google's personal file storage plans, Jeff Chester, the executive director for the Center for Digital Democracy, raised concerns that are applicable to "My Location" as well.

"Google wants to become the global private Ministry of Information," Chester said. "It's all about allowing Google to mine our personal information so it can reap the revenues. Instead of protecting privacy, Google's data collection-dependent business model is increasingly become a serious threat to consumer welfare."

The key question is not whether companies will pay to advertise to anonymous mobile users (newspaper ads are a good example of anonymous advertising), but whether the additional amount they'll pay for non-anonymous ads will persuade cell phone companies and even Google to connect the electronic dots.