The Register is up in arms about something that's been done by companies for nearly a decade now, only it's suddenly important because Google is doing it? Say it ain't so!
Seriously. All they're doing is collecting publicly available wifi information - the SSID and MAC of the wifi access points as they trundle around. Companies have been doing this for years and geotagging them so that wifi devices can figure out where they are without GPS. Google was, until recently, using some other company's database for this information, but they now have their own database that says, "If you can see this router, then you are probably in Austin, Texas near Main street and River street." They collect the MAC because the SSID can change (so, too, the MAC, but not as easily).
I love the line about how the spooks would love to have this information so they can match people with their MAC addresses. The MAC address is not transmitted over the internet, so you can have all the MAC addresses of all your own citizens and you aren't going to know anything new or interesting about them, unless you join their LAN.
The article is just another bunch of hogwash intended to sell papers/webviews. Yes, there's truth there, and it is somewhat interesting, but it's of no real importance or significance.
Having a wifi access point in your house is like conducting all your conversations by yelling. A neighbor next door or traveler outside may listen in all they want, and identify you by voice. You can yel in code, in which case they won't be able to tell what you're saying, but they can still characterize your voice and identify it as the same voice later on.
If you don't want people to listen in on your conversations, don't shout (ie, don't use wifi, or make sure the radio transmission never leaves your property using a Faraday cage). Alternately, speak in code (ie, use WPA2) and realize that people may still be able to walk by later and say, "yep, same person that was shouting there last week - I must be close to my destination."
