Big data is like a fashion trend: You can't turn around without seeing yet another magazine article, research report or talking head pontificating on why you can't live without it. In this case, however, the trend-pushers have a point. Case studies at the Gartner Business Intelligence Summit added to a growing body of evidence that a company's ability to collect, process and analyze large data sets could mean the difference between success and failure. Leadership -- on the IT and business side -- is key.