Given the smaller size of the iPad Mini, Apple’s latest entrant could be a play to drive meaningful tablet ad revenue, says Ashley Swartz in this commentary on new devices from Apple and Microsoft. Apple needs to build a new revenue stream from its mobile platform to effectively compete with Amazon and others in the mobile ad arena, Swartz says. For now, Apple is primarily deriving mobile device revenue from iTunes and apps, but needs to move beyond that to monetize ads as well, Swartz posits.