When Google provides location-based services on mobile devices, the quickest way it obtains a user's coordinates is by checking the location of nearby wireless access points and triangulating from there. That means that your humble Wi-Fi network may oftentimes serve an unwitting role in Google's epic plan for ubiquitous information. Of course, the Mountain View team is hardly alone in obtaining Wi-Fi-assisted location data in this way, but today it's giving users some form of redress by letting them opt out.
The onus is on you to do the legwork, as you have to append the term "_nomap" to the end of your wireless network name — so if your network's called "Verge," you'll need to dub it "Verge_nomap" — which will tell the Google Location Server to ignore you when looking for nearby networks. Yes, having to tinker with your router's SSID will be tedious for most and unintuitive for newbies, but at least you have an option today that you didn't yesterday. Additionally, Google hopes that other location service providers will choose to also adhere to the no-mapping instruction, which could eventually turn it into a de facto standard.