But I'm thinking, more so than Pinterest it's closer to "Path" where you and your small network of close friends collectively get a deal (at Jerry's liquor, lovely example) then post cute photos of your night/experience (sans the trip on the porcelain bus) which become public on "Jerry's Drive-In Liquor" or whatever, and exposes the deal to other people in the private networks of those who were in your private network... a sort of "local viral" marketing effect which works as advertising and as the regular "look how awesome my saturday night was" that we (what? just me?) use Facebook/Instagram for anyway.
I think it perfectly combines the innate desire to show off and receive value while maintaining an air of exclusivity plus the whole validation thing, from strangers and friends alike.