By and large big business has not cottoned on to the use of Social Media in general and Twitter in particular. There are some businesses, for example, Dell computers who fully appreciate the power of Twitter and have thrown a considerable staff resource at it. Well, I here you say, "they would because they are in IT and Twitter is sort of IT because it's on the internet".
Well, Social Media and Twitter are not IT they are communications in the broadest sense and a large part of business communication is marketing and sales. The beauty of Twitter is that it can be targeted, is immediate, and best of all, it is free. You can actually measure its effect unlike advertising outside of the internet.
If you are in a large business and not using Social Media Marketing techniques including Twitter, I suggest you start tomorrow by appointing a Social Media expert. Your IT department and marketers cannot do it without training.