I spent $3.58 on that mocha. If I’d only joined Blippy - a social-media app that posts the purchases of its members both on the site itself and to their Facebook and Twitter accounts -yesterday, I could have updated my Facebook with a $65 ski lift ticket, an obscene amount for top-of-the mountain snacks and, unmentioned but casually obvious, the fact that I spent the day at Killington. My first thought is that no one would care, but we all know Facebook, Twitter, and the like aren’t about sharing important or even interesting info. They’re about maintaining a vague, loose connection with a couple hundred close personal friends. So if you are what you buy, and you tweet what you are, Blippy (which can link to a credit card or to accounts with iTunes, Netflix, and others) was inevitable. Blippy calls it passive sharing (although, depending on the purchase, I could see passive-aggressive sharing: KJ just bought The Lazy Husband !) and suggests that you’d have one credit card as “the social card” and one for, ahem, other stuff. (KJ just bought a 30-day supply of Prozac! And maxipads!) I could actually see a use for this, although rather than posting my purchases to Blippy, I should just arrange to have them e-mailed directly to my mother, which would curtail my discretionary spending substantially. I can also see the fun in it-some of what I buy does indeed say something about who I want to be, and some of it does start conversations with friends. (Could this be the solution to the annoying acquaintance who always wants to know where you got it and what you paid?) I can certainly see the utility to advertisers, and even the possibility of a Blipster discount. So Blippy may take over. But in writing this, I can also see that it hasn’t yet taken off-that scroll of purchased items on their site either isn’t live, or Ross has purchased the MLB app five times in the past 15 minutes . Maybe there is a limit to what we want to share.