Google announced that in an effort to increase transparency and great user flexibility, there will now be a sidebar widget on Google that will show your current browsing location. It will also allow you to easily change your browsing location to see local results from a different area.
Google will automatically detect your location based on all the same factors it has always used. Your manually set location will be saved in a browser cookie on your specific computer and internet browser only. When you use the same computer and browser, this manually set location will be used to customize your search results instead of the automatically detected location.