Grab bag: Defining success Shepard Fairey, success – Exhibitionist – Boston.com “Accusing Shepard of vandalism is like handing out speeding tickets at the Indy 500.” (tags: shepardfairey) Twitter is now worth like half as much as it was last week (Marc Canter) As Facebook moves toward open systems, how much longer can Twitter hold out? (tags: twitter facebook) Chicken pie with biscuit topping (Boston Globe) A winter favorite. (tags: recipes cucina)