There are two reasons why this is legal. First, the recording happened from a public space. And second, the recording was made with a device in general public use -- a camera.
Any outrage expressed by the person broadcasting his password via electromagnetic radiation (light) into the public space would be ludicrous.
In fact, there are many ways to use electromagnetic radiation to broadcast personal data into the public airwaves.
One could say "My password is bond007" into a walkie-talkie, a ham radio or a CB radio.
It's perfectly legal for a passerby or anyone else to listen to and record that audio signal, as long as he's in a public space or in his own home.
Even if the broadcaster is ignorant of the fact that speaking into a radio conveys his voice into the public space, it's still not illegal for someone else to listen to it or record it.
In each of these cases -- the TV in the window, the walkie-talkie, the ham radio or the CB radio -- the data is being broadcast via electromagnetic radiation out into the public airwaves and therefore it is not a violation of privacy for someone else to receive and record the data.
A Wi-Fi signal is exactly the same thing. It uses electromagnetic radiation to broadcast data into the public airwaves.
As in my thought-experiment, it's up to the owner of the equipment to determine whether and what data is broadcast publicly.
When someone sets up a Wi-Fi network and a Google Street View car drives by and captures the data, it's not that Google is invading the home. The Wi-Fi signal is invading the Street View car on a public road.
I believe the burden is on anyone who says Google's data harvesting is illegal to explain why recording data voluntarily broadcast into publicly owned airwaves over one part of the electromagnetic spectrum is legal, but doing so over another part of the spectrum is illegal.
What's the difference?
It's not as if the equipment that's needed to view and record such data is hard to find. You can buy it at Wal-Mart, and nearly everyone owns such equipment.
Look, Wi-Fi is no longer some new, mysterious and rare phenomenon. It's not witchcraft, or some unknown to be feared and confused about.
I think we can all agree that anyone who broadcasts unencrypted, un-password-protected data over public airwaves in a way that is readable by devices millions of people own has no reasonable expectation of privacy.
And anyone who views, records or "harvests" such publicly broadcast data has -- and should have -- every right to do so. The hysteria around the so-called Google "WiSpy" scandal represents an ignorant double standard about data voluntarily broadcast over public airspace.
Give it a rest. Google did nothing wrong.