Gartner analyst Tom Austin has been on the road finding out what makes enterprise social and collaborative projects succeed. He's boiled it down to ten particular success factors. Defining success (and agreeing upon that definition), working with people in across silos and with different skill levels, and being well aware of the starting conditions are key. Have you lead a successful social or collaborative deployment? What factors were important?
You can read Austin's whole post here. I'd also recommend checking out our articles 5 Principles for Improving Social Enterprise Adoption and Enterprise 2.0 Adoption: Does It Have To Be So Hard? for more insights.