@spodula
"Remember, all google were doing was recording network IDs."
Get the facts strait, they recorded entire packets. This is mostly what the controversy is about.
"or tell your router not to broadcast its SSID."
Technically, the broadcast is a public announcement about the AP, but apparently google recorded actual private traffic, which includes the SSID. Not broadcasting an SSID may change the legal status of connecting to the AP, it certainly doesn't stop the snoopers (like google) from sniffing it.
Micky1
"The MAC, SSID and GPS coords are NOT personally identifiable information. You cannot use them to find out who a person is without a 4th dataset that most people wont have access to (e.g ISP records)."
Like an IP, these may or may not identify a single "person". Never the less, it could still reveal the address of someone at a hotspot or hotel after their SSID has been recorded. With the scale of google's dataset, it's possible they could pull it off.
As for correlating the SSID to other accounts, this may be possible (for example) by capturing the user's traffic as they're connecting to email/google/theregister, and extract personal information that way.
Given how often IMAP/POP checks for email, it's very likely google captured some of these active sessions.