Google is making it easier to identify where some sites exist geographically. Normally, you can tell this information from the URL, such as .ca for Canada or .br for Brazil.
But when it comes to TLDs such as .com and .net, it's not always clear. Google is adding country-specific information to the green URL line in the search results. Here's an example per the Google Webmaster Central blog:
You can tell Google what country your web site is associated with. Log on to your Webmaster Tools account. Then go to Site configuration > Settings > Geographic Target.