Griffin Technology. The make iPod accessories and such.
Wait, I am not sure the President would want to be on Twitter at all. However, Citibank runs ads and marketing campaigns, they have customer service, they run PR campaigns. Twitter is a tool that those departments can use to actively listen and respond to their customers.
I hear the "Instant awareness" thing. I should probably look up an example of this before I go in though. I think I read an article about that here a while back (how Twitter is a potential competitor to Google because of its faster reaction to changes in public mood)
I don't think the customer service angle will work in the context of the company I'm dealing with. The company has certification programs and its main product is in use with banks and other large companies - I don't think the president of Citibank is going to twit about how XYZ screwed up big time. (That said, I wonder if I can explain how it might be a good way to reach out to hacker-types)