Google Says It Mistakenly Collected Wi-Fi Data While Mapping
Even if Google says there's nothing to worry about, newviewmedia.com writes, the company "said it would stop collecting Wi-Fi network data from its StreetView cars, after an internal investigation it conducted found it was accidentally collecting data about websites people were visiting over the hotspots.
From the WSJ article: 'It's now clear that we have been mistakenly collecting samples of payload data from open [i.e. non-password-protected] Wi-Fi networks, even though we never used that data in any Google products.'"
AP information is packet data (they're called beacon frames). Looking for beacon frames is a lot more effective at finding APs on the move than using whatever built-in scan feature your card drivers have. They probably had a SNAFU and forgot to filter out data packets in their capturing setup, instead storing everything that hits the antenna (or some engineer didn't realize it would be an issue).
I wonder if they were using "off the shelf" open source tools to collect this information.
By default Kismet will log the pcap file, gps log, alerts, and network log in XML and plaintext.
http://www.kismetwireless.net/documentation.shtml
It is entirely possible that they were using off the shelf open source tools and this log type was simply not turned off in the configuration file.
Remember that you are unique, just like everybody else.