Apple’s latest patent application, revealed today, could add a whole new (and huge) dimension to the exploding smartphone app market: Phone-to-Phone app sharing, with incentives. It’s like Groupon and social networking meets the App Store.

The idea rests on an “Application Seed” system, which means iPhone apps would include a specific code that identifies the app, along with a secure identifier and other data such as which servers to find the app on, or which devices it could be enabled to run on. Call it a smart fingerprint.

App discovery happens in many ways online–surf to a review site, or iTunes, or see a promotion on a website, then click on a hyperlink, sign in to your iTunes account and download and install the app.

Yet there’s one important means of app discovery that is untapped by Apple, and that’s person-to-person recommendations. We’ve been there: Someone uses a clever app on their phone, we get impressed, but we have to jump through the usual hoops to find it, download it and install it. Apple’s system would simplify this process, and it would offer incentives to the “promoter” of the original copy of the app. Suddenly, that guy showing off his iPhone’s latest tricks at the water cooler becomes a little bit wealthier.

The sharing system would require the original app owner to enable sharing of the app inside their own device, perhaps by dragging it to a special portion of the homescreen. The recipient’s phone would identify the sharing offer automatically–either over a wireless peer-to-peer network, or regular Wi-Fi or 3G. We imagine Apple’s interest in near-field tech could also come into play. The app owner and the app recipient may only need to touch their phones together.

After the application seed is exchanged, a couple of different things can happen. The app could be written to contain a raw copy of itself, which could then be directly transmitted. Or it could contain a partial or demo copy (ready to entice the recipient to buy a full copy). Or the exchange could instruct the recipient’s phone on how to acquire the app.