Yes, the iPhone supports client-side SQLite databases, accessible from JavaScript, and it has the ability to cache web resources, so that they can be used witho

Yes, the iPhone supports client-side SQLite databases, accessible from JavaScript, and it has the ability to cache web resources, so that they can be used without network access (again, from JavaScript, you can tell whether you have a network available, and change application behaviour accordingly). Those are both from open standards. Web sites can also declare themselves to be "web apps", in which case the user can link them to the phone's home screen, and they can look just like native apps, with splash screens on startup; even hiding the usual safari navigation if you want.