Add the mobile piece to social shopping + social networking and we just might have a new killer app (i.e., huge uptake). What I’m talking about is Facebook’s just-announced “Deals.” Analysts are saying social shopping (users giving products in virtual stores, or Web sites, a “Like,” review, or comment) was ho-hum. What really adds interest and potential mass appeal is a pay-off, the BBC reports – such as “a free pair of jeans to the first 10,000 users who check in to their local Gap store using Facebook’s mobile [Places] application.” The BBC adds that the Gap is just one of “22 major retailers [FB has partnered with so far], including H&M, Starbucks, McDonalds and the Palms Hotel in Las Vegas.” Can we see a certain appeal, here, to teens? The thing to think about (hello, Facebook?) is the possibility of teens thinking more about the free-product part of this equation than the location-sharing part – and who they’re sharing there location with, including third-party app developers who may not be as conscientious about what’s done with that information about minors. How can Facebook police the security practices of the hundreds of thousands of apps on its site, is a question my ConnectSafely.org co-director Larry Magid asked, referring to the higher level of protection needed for disclosure of location. Facebook told the BBC that it shuts down any of the 550,000 apps and games on it site which violates its terms of service. That’s great, but how does it find out about violations? The BBC reports that “last week, Facebook pulled the plug or denied access to ‘communications channels’ on around a dozen application developers who violated their terms of service.” So far there are four kinds of Deals, PC Magazine reports: “individual deals, loyalty deals, friend deals, and charity deals. There’s even a UI that shows ‘punches’ on a virtual card for loyalty deals, Facebook says, with discounts for users who bring new friends and customers.” Here’s Facebook’s blog post on this development.