The specific text reads: "If you build your application with features based on a user's location, make sure these features provide beneficial information. If your app uses location-based information primarily to enable mobile advertisers to deliver targeted ads based on a user's location, your app will be returned to you by the App Store Review Team for modification before it can be posted to the App Store."
Developers began noticing the "App Store Tip" and suggesting the underlying message is that Apple wants to reserve location-based ads for themselves to either utilize or control. Other outlets picked it up, largely agreeing with that analysis.
We do know Apple acquired mobile ad network Quattro Wireless, ostensibly to make a concerted push in this space, which stands to become extremely hot over the next few years. We don't yet know what their exact plans are, but this developer-facing post certainly seems to hint at Apple's intent to heavily mediate how location-based advertising will be handled on apps for the iPhone. For now, developers should brace themselves for rejection if a submitted app contains a hook that "primarily" enables local ads.
What do you think: is the developer tip an early warning sign about Apple's own mobile advertising foray, or is there an alternative explanation for alerting developers about local ads?