Writing at Forbes, Mark Evans has advice for startups that would also serve sales professionals:

In many ways, social media becomes dangerous because it can be distracting and time-consuming. There is so much belief that social media can generate major benefits that it’s all many startups embrace in terms of marketing.

Sites like Facebook and Twitter are useful tools — I use them myself — but they’re no replacement for tele-prospecting, in person introductions, and relationships with prospects in which you can build likeability, trust, and influence.  Use social media, but keep your eye on the prize.