It's what you know.
Adam Bosworth Founder and CEO, KeasEvery company is trying to figure out how do we get our employees and our consumers to do the things we want them to do. With Facebook, we started with who you know, and we're going to see a big shift from "who you know" to "what you know" to "what you do."
In the "what you know" department, the contenders are companies like Jive and User Voice, all of whom have been figuring out how do we take who you know and use them to provide customer support in the best way possible and in a way that flattens the organization and blurs the employees and non-employees. My vote would go to Jive as the one that matters three years from now.