I noticed Google asks to do this in Android, too. They make you explicitly OK it though, at least on my (Verizon Droid) phone.
In location options, if you check certain options it warns you that Google will be logging wifi info and other details even while apps that access this info are not running.
The warning shown when you click "Use wireless networks" in Location settings is
"Location consent
Allow Google's location service to collect anonymous location data. Collection will occur even when no applications are running."
My analysis is that this turns the phone into a mobile sensor that performs the same function as one of the Google mobiles driving around with cameras performs relating to wifi and location logging. Google probably collects the GPS coordinates and SSID of every wifi network that comes into range of a phone with this enabled. Given their recent legal troubles relating to wifi discovery, hopefully it doesn't gather more than that.
Yes it does scan surrounding wifi SSID because Google Maps uses Skyhook ( http://www.skyhookwireless.com/ , belongs to Google) to geolocate users faster than just using pure GPS signal. So does Apple which also use Google Maps geolocation services on their iPhones.
My guess is that Apple is gathering all those data in order to build their own Skyhook. It makes sense, specially when you keep in mind that Apple bough the mapping company Poly9.
In location options, if you check certain options it warns you that Google will be logging wifi info and other details even while apps that access this info are not running.
The warning shown when you click "Use wireless networks" in Location settings is
"Location consent Allow Google's location service to collect anonymous location data. Collection will occur even when no applications are running."
My analysis is that this turns the phone into a mobile sensor that performs the same function as one of the Google mobiles driving around with cameras performs relating to wifi and location logging. Google probably collects the GPS coordinates and SSID of every wifi network that comes into range of a phone with this enabled. Given their recent legal troubles relating to wifi discovery, hopefully it doesn't gather more than that.