Do social networking sites benefit engineering businesses?

I am the marketing coordinator for American Engineering Group LLC. I would like to know how much social network sites helps for marketing the engineering business. I was referring to some websites and people usually refer that big giants and well established companies get the most out of social networks. Is that true?

Please let me know your viewpoints. Any help would be appreciated.

Thank you
American Engineering Group LLC
http://www.engineering-group.com (for more info about our company)