Should Business-to-Business-Companies care about Social Media?

When we talk about successful usage of Social Media one often talks about nice brands targeting end customers. Not only because there are many of good examples but also because they are more visible than others. But being a company doing business to business products or services one wonders what to do with social media. You barely establish your brand with it, only few try to do business to business over the social networks like Twitter and Facebook yet. Asking themselves: Should I care about Social Media?