Have you heard? Social media isn't a fad! In a study sponsored by Nielsen-killing-hopeful TNS, more than 50 percent of "senior marketing executives agree that the use of social media for corporate, brand and product marketing" is here to stay because it's tres important. "Poking" friends is productive! Which is all well and good, but before you begin dumping a few million dollars (or several hundred, in the case of Microsoft and Facebook), just 18 percent of those surveyed thought social media would increase brand loyalty. So heads up to Sprint, where some 638,000 customers are defecting: Don't bother with Facebook ads. [MP]