Walmart the popular store has developed an iPhone specific application. If you access the homepage of Walmart from the iPhone, you will be greeted with an iPhone specific portal that will help you with your shopping. You will be able to browser through different categories and products in them, access the recent product specials, search for a local store/product and see a $4 approved prescriptions.
If you use the application frequently then you can create your own shopping list by going to the Shopping List tab. Though these features are available, you still can’t buy a product through iPhone, for that you have to visit the regular site.