The Cupertino company recently purchased the mobile advertising company Quattro for $275 million.
More recently, we saw glimpses of Apple's mobile advertising future in an "App Store Tip" they published which discouraged developers from creating apps that "use location-based information primarily to enable mobile advertisers to deliver targeted ads based on a user's location." Because that's exactly what they want to do themselves, of course.
Rumor has it that iAd will debut on April 7th, 4 days after the iPad release. Either way this is another glimpse of how Apple plans on taking over and dominating online 'everything' as we know it...