Para la visualización de páginas HTML5 en navegadores que no lo soporten.

• http://www.modernizr.com/

Geolocation

if (Modernizr.geolocation) {
  // let's find out where you are!
} else {
  // no native geolocation support available :(
  // maybe try Gears or another third-party solution
}

* http://code.google.com/p/geo-location-javascript/

//determine if the handset has client side geo location capabilities
if(geo_position_js.init()){
   geo_position_js.getCurrentPosition(success_callback,error_callback);
}
else{
   alert("Functionality not available");
}