The challenges facing brick-and-mortar stores are only growing as online shopping moves from the desktop to smartphones. People look up prices online while they're inside a store. They make purchases from an online store unconnected to the store where they're roaming the aisles. The list goes on.
Walmart's app is customized for each store.
This is why Walmart -- a company known far more for its data mining and supply chain mastery than for its mobile apps -- is going all out with mobile. The idea is not to make it an either/or option; instead, Walmart's iPhone app (Android is coming soon) caters to people who are first and foremost shopping inside a Walmart store.