I was recently asked to answer the above questions, here is my response:
Who needs a librarian/information specialist? Everyone! A librarian is trained to meet user needs, this means helping people find what they are looking for, directing them to the proper places to find what they need, and helping them to use the tools they need to find what they are looking for. Sometimes this is referred to as information literacy, according to the American Library Association, “To be information literate, a person must be able to recognize when information is needed and have the ability to locate, evaluate, and use effectively the needed information.”
Further, a librarian is dedicated to information access for everyone, without passing judgment on what it is that the user seeks. A primary aspect of information access is protecting the privacy of the users.
A librarian is dedicated to sharing information, and thus creating and sustaining networks of information such as databases, intranets and internet sites. Not only does a librarian share information, he/she finds and organizes information in order to make it usable. In this day and age, this means using technological solutions…
Elizabeth Gould 
Okay… So how would you apply this to a team of researchers? When I read this I’m thinking it applies more in a public context. But how about in our context? I’m dragging you into the whole knowledge-sharing/knowledge-management world…
Oh, you want to know about an information specialist, not a librarian. A librarian works in a library! E
But some librarians work for organizations. No? IDRC, for example, hires in-house librarians. So do law firms. But OK then… information specialist… Our context. The piece I can use from above is the last para. Anything more?
Hmmmm. I suppose part of the answer is in this post YOU sent me! http://www.information-management.com/blogs/metadata_editor_metador-10016283-1.html