A small, but interesting note: Apple's published an "App Store Tip" for developers that it'll reject apps which "use location-based information primarily to enable mobile advertisers to deliver targeted ads based on a user's location." It's not to protect you.
Instead, what Mac and iPhone developer Craig Hockenberry almost certainly correctly surmises, "Looks like Apple is going to keep location-based advertising to themselves."
Let's step back for a second. Apple, as you might know, spent $275 million on the mobile ad company Quattro, after previously trying to acquire AdMob (before it was snatched by Google). The CEO of Quattro is now VP of Mobile Advertising at Apple. Apple has now openly declared itself a mobile devices company. And according to BusinessWeek, Apple's working on "ways to overhaul mobile advertising in the same way they had revolutionized music players and phones." Apple is serious about mobile advertising. That's point one.