A Check In App worth Checking Out?

I’ve never been crazy about location-based check-in apps. I’ve used them a few times to support friends in contests or to get a discount on food, but the reward has to be pretty good for me to open an app and actually check in. I recently read about Shopkick in the NY Times. While Foursquare is a social tool, Shopkick is a passive check in app that actually rewards consumers for walking into a store. Currently only available for the iPhone, Shopkick's free app dispenses “kickbucks” reward points for entering the store. "Kickbucks" can be redeemed for anything from gift cards to product discounts to Facebook credits. How does it work? A transmitter in the store emits a signal that’s detected by the app on the consumer's phone. For each kickbuck a customer earns, Shopkick earns a small fee, the New York Times reported; for each purchase made after using the app, Shopkick gets a portion of the price. I haven’t had a chance to use it yet (just a few stores have it in Dallas) but I feel like I've seen this idea somewhere before. The system seems perfect...until it comes after you.