One of the most powerful tools that iPhone app developers can leverage is Core Location via the CLLocationManager Class. The upshot of this technology is that the user's own physical location is accessible to the app, allowing for locally customizable information delivery and search services; such as a current weather report — or the nearest Starbucks.

While privacy advocates decry such personal information being revealed to third parties, entrepreneurs have been going full steam ahead with efforts to develop apps that will, for instance, download a digital discount coupon when you walk into (or near) a retail store or restaurant. Or even a chit for a free lap dance at the strip club just around the corner.

The possibilities are amazing, endless — and of course, of concern to Apple, which is taking a stance against advertising-driven locational apps.

"The Core Location framework allows you to build applications which know where your users are and can deliver information based on their location, such as local weather, nearby restaurants, ATMs, and other location-based information," states the Apple Developer website, which also warns that "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," the site continues.

As an example of the distinction, consider the GEICO insurance app that the little green gecko demonstrates on one of the company's many television ads. One of its most useful features is a service station locator that shows users the location and contact information of the nearest tow truck. Invaluable aids when broken down in the middle of nowhere, as you not only have the means to call for help, but can pinpoint your own location.

That seems perfectly acceptable to Apple.

However, an app with that same feature, offered by a different company and based upon paid listings (think of a "Yellow Pages" app), that charged a fee for service stations and tow trucks to be listed in it, would likely be rejected under these new policy guidelines.

While it's outwardly admirable that Apple is taking steps to spread its corporate altruism, there may be other motivations than limiting spam farms from the App Store. Keeping any potential competitors out of its own backyard may be playing an even greater role in its reigning in of app development business models.

Earlier this year, Apple acquired Quattro Wireless, a mobile advertising network, in a $275 million dollar deal — a move which followed Google's acquisition of competitive mobile ad network AdMob. Clearly, these major stakeholders are investing heavily in the future of locational-based mobile advertising — and trying to keep others from following suit, at least too closely.

There are also the technological advancements in the sophistication of ad targeting and delivery that are in play, and developers may see resulting patent licensing and other issues come up as the local services market heats up.

"In mobile we are seeing that when phone numbers and coupons are offered people are much more likely to click on the mobile ad," Google product SVP Jonathan Rosenberg said. "Well, imagine if [a store's] inventory information is there so they can actually consummate a transaction locally. As that information becomes available, local is going to be much, much more powerful."

Developers may download a sample of the LocateMe code from the iPhone OS Reference Library at the iPhone Dev Center.