Many web sites aim to deliver local content these days, and do so even without you providing your location. The tactic has been done for years with reverse IP lookups that associate your IP address with your ISPs router location. Online tools demonstrate this such as Geo IP Tool & DomainTools). It’s analogous to tracking a phone number starting with (213) to Los Angeles. The precision is generally only accurate to a zip code and is sometimes completely incorrect. But recently, Google has demonstrated that they can geolocation you literally right inside your house.
It’s called Location aware browsing and its determines your location in a novel way. You’ve probably seen Google Street View; well it turns out that Google collects more than pictures when driving around, they also triangulated the position of wireless hot spots in your area. And when you’re using Firefox or Chrome, your computer tells Google which hotspots it sees and with some basic geometry, voila, your pinpointed!
You can activate the feature to show you what it knows about your location by going to 
Google Maps and clicking the “Show My Location” located above the zoom slide bar. It does ask for permission to share the location information (look for the “Allow” popup at the top of the browser windows), which is somewhat ironic since Google already has the information. If computer doesn’t have wifi or its disabled; the feature will probably not work.
Regardless of your own browser of privacy choice share, Google has established a great system to estimate you and your networks geolocation with a degree of precision of dozens of meters in many cases. It’s likely that this information is used in filtering highly targeted local search results. Although the feature and authorization requests are optional, Google has amassed its own reverse IP database far more accurate than previously known.