Foursquare has become a popular mobile social networking app with some shopping perks.
But another iPhone app, launching today, is much more focused on shopping, and has the combination of early deals, big-name backers, and buzz that makes it worth watching.
Shopkick, a San Francisco-based startup, launches its flagship iPhone app today, and it's right at the interesting junction of mobile apps, location-based services, and commerce. Someone is going to make money here someday, and Shopkick is one of the most ambitious, interesting attempts we've seen. (Click here to get the app in iTunes.)