I couldn’t say it any better than this paragraph from a recent Advertising Age article:
Most analysts who watch this space will tell you the same thing: Most marketers think they can simply take their mainstream advertising efforts and activate them on these networks under the assumption that they will flourish. Not only does that completely miss the boat, it also completely misses the driving concept behind an effective existence within social networks. "Frequency of message is not the idea here," Mr. Murray said. "Frequency of contact is." Charlene Li, VP and principal analyst at Forrester Research, also said marketers haven’t seemed to figure out that this is a channel where consumers actually want to be spoken to. "[Consumers] are asking questions on these sites that go unanswered," she said. "You can’t ask for a better environment. And what do marketers do? They say nothing and put up another ad."