As you may know, Google is building a database of wireless access points to improve its location database. If you don't want to be included in the database, Google recommends adding a "_nomap" tag to your routers' SSID:
The wireless access point information we use in our location database, the Google Location Server, doesn’t identify people. But as first mentioned in September, we can do more to address privacy concerns.
We’re introducing a method that lets you opt out of having your wireless access point included in the Google Location Server. To opt out, visit your access point’s settings and change the wireless network name (or SSID) so that it ends with “_nomap.” For example, if your SSID is “Network,” you‘d need to change it to “Network_nomap.”