Google's global privacy counsel provides a detailed explanation about what data Street View gathers, including Wi-Fi signal information: As I wrote about last week, Germany's data privacy commissioner raised an alarm at Google scanning and recording data about Wi-Fi networks as it drives around snapping Street View pictures. The commissioner is off base in stating that publicly identifiable information is being grabbed, but perhaps it's better that a privacy czar errs on the side of the public at times.
Google's corporate counterpart to that commissioner, Peter Fleischer, penned a blog entry in which he explains in excruciating detail precisely what data is being collected in what fashion.
He writes, in response to the ersatz question, "Is it, as the German DPA states, illegal to collect WiFi network information?":
We do not believe it is illegal--this is all publicly broadcast information which is accessible to anyone with a WiFi-enabled device. Companies like Skyhook have been collecting this data cross Europe for longer than Google, as well as organizations like the German Fraunhofer Institute."
He does not note that Wi-Fi intentionally publicly broadcasts technical information for adapters to use to join the networks. Network users who don't want this information broadcast can disable beaconing (making it a "closed" network), or stop using Wi-Fi, or--to reduce range--even drop signal strength on many routers, or, in the 5 GHz band in some countries, choose a lower-numbered channel that uses far less signal strength than higher-numbered channels.