HTML5 Caching: AppCache and LocalStorage

So we've these brand new toys in HTML5 like appcache (offline caching) and Local (or session) storage to build fast mobile web apps. You would say appcache would be used to improve load speeds on mobile devices. But many big companies are actually using localstorage instead for caching purposes. Making me wonder if this is the new mobile browser cache? Indeed it seems many developers are using localstorage because of certain issues (page that includes manifest is always cached) with appcache, making some people wonder if it could be used effectively at all in a dynamic environment like Drupal.