In a Google blog site, Peter Fleischer, Global Privacy Counsel, wrote, "Even though the wireless access point signals we use in our location services don't identify people, we think we can go further in protecting people's privacy. At the request of several European data protection authorities, we are building an opt-out service that will allow an access point owner to opt out from Google's location services. Once opted out, our services will not use that access point to determine users' locations."
Google says it collects this information so that its location services will work better. "Google Maps for Mobile, for example, helps people find themselves on a map and then locate places nearby," Of course, you probably already know where you're at. I'm in my office. No surprises here!
Seriously, this information is useful for any location-based service. Yes, you can use GPS, but Wi-Fi amd cellular phone tower-based geographical information helps nail your location when you ask for say directions to the nearest coffee shop.
Google Street View vehicles collect your Wi-Fi AP's unique MAC (Media Access Control) address, network name and location as it drives by. Since most access points stay in the same place, Google can use this data for its location-based applications.
That's good for location-applications, but although Google doesn't correlate your location with your AP and physical address, let's face it; it wouldn't require a lot of work to narrow down where you're likely to be found when you combine your AP data, the corresponding Street View photographs, and your ISP information.
So, if you're on America's Most Wanted-or you think you have a very tech-savvy stalker chasing you-you really don't want your AP's data to be collected by Google.
You can't stop it yet though. According to Fleischer, "We'll be making this opt-out available globally, and we'll release more detailed information about it when it's ready to launch later this autumn."