As I read, by adding "gl" parameter to Google search queries will show search results localized to the country specified by the parameter. For an example following will fetch results that would be shown in US, http://www.google.com/search?q=gift+shop&gl=us How effective this has been? I tested ranking of a site for a particular keyword on Google using this method (setting gl=us) and it was 108. Then I asked a friend in US to do same search without specifying any parameter manually. He found the site in 67th place.
it is effective search string. however, depending on which datacenter the results are pulled and where the query was searched, you may see different results
i tried the following:: http://www.google.com/search?q=gift+shop&gl=uk and then:: http://www.google.co.uk/search?hl=en&q=gift+shop&btnG=Google+Search&meta=cr%3DcountryUK|countryGB both are showing results quite similar