I've seen a few articles and discussions recently converging around the idea of defining what a "librarian" actually is. The March 2005 issue of American Libraries has a cover story about paraprofessionals working in libraries and the perceptions of them by patrons and "librarians" at their place of work, there has been an ongoing thread with the subject "End of Librarianship" over the Autocat mailing list weeks 1 and 2 of March 2005 (browse the archives), and a posting today at lisnews.com reporting a library director job indicating an MLS was optional for applicants. These all touch in some way on whether an MLS, a job title including the word "librarian," or a job in a library makes one a "librarian."
Certainly the definition of "librarian" is contextual. The American Libraries article asks some library paraprofessionals what their answer is to the question "Are you the librarian?" Since a patron asking that question almost certainly means "Can you help me?" rather than "Do you have an MLS?" or "Does your job title say you're a librarian?" so the answer there in my opinion should be an emphatic YES.
But many librarians are extremely protective of this label. It represents a significant investment of time, money, and intellect into earning a professional degree. And that's certainly nothing to sneeze at. (Even if some MLS programs in this country today can't reasonably be described as "rigorous.") However, I certainly know a number of people in jobs with titles including "librarian" who were hired under the rationale "MLS or equivalent experience" who do excellent jobs. Shouldn't one's ability to perform the duties of a position be the primary criterion for hiring them? I tend to think that a piece of paper bearing the designation MLS doesn't necessarily tell an employer whether or not an applicant is qualified.
I guess the argument comes down to whether the term librarian should refer to "what you do" or "who you are." And I can see how each would be appropriate in different circumstances. I tend to believe one should demonstrate his or her skill and professionalism in their interactions with people and in their work performance, rather than assuming an acronym and a diploma are an accurate indication.