One of the ways Google tracks where you are for its location-based services is via a list of known wireless routers and access points. While that list doesn't include personal information, if you'd rather Google wasn't tracking your router or access point at all, there's now an easy way to make that happen.
All you need to do is change your network name (the SSID) so that it ends with "_nomap". Changing the name usually requires logging into your web-based configuration page, a process which will vary depending on the hardware you use and may require you to connect via ethernet. Google has a help center article which covers the basics for many popular models.
Unfortunately, this does make it harder to use a quirky name for your network, though I guess "I_have_nomap" or "LottsaVirus_nomap" would still work.
Greater choice for wireless access point owners [The Official Google Blog]