I spotted an interesting video about Maersk Shipping's social media efforts. We tend to associate B2C with social media but it's for B2B too. I mean Maersk is a shipping line---why do they have over 205k likes on Facebook? (By comparison Salesforce only has 78k likes)
But it makes sense. A better overall image for the brand at large---and (believe it or not) the shipping community is a vibrant online community (see gCaptain.com).
Additionally, a social online presense probably helps with recruitment, collecting data and monitoring brand perception, and if a crisis ever arises these online roots will prove invaluable.
Also: World's Largest Ship (Maersk site):
http://www.worldslargestship.com/
And BTW: Does the social media expert in that video look like Jack Nicholson in The Shining? Hereeeeeeee's Johnnnny!