uses Google Maps API for jQuery autocomplete

geocode-autocomplete.js

$(function(){
  var geocoder = new google.maps.Geocoder();
  
  /* use Google Geocoder in jQueryUI autocomplete widget */
  $("#search").autocomplete({
    minLength:8,
    source:function(request,response) {     
      geocoder.geocode({address:request.term}, function(result,status){
        var addresses = jQuery.map(result, function(address){ return address.formatted_address; });
        
        response(addresses);
      });
    }
  });
});