A Roving Librarian is one who realizes and acts on the understanding that the campus is their classroom. The "campus" means not just students but administration and staff. It is the concept of providing research instruction beyond the library's walls. Becoming a Roving Librarian frees you from the Research Help Desk.
Yes, there can be roving within the library building, but why be tied down to that? With Wi-Fi on campus it was a given to take research instruction outside the library and on demand. Outside the library includes not only other buildings but outside campus buildings as well.
Why not go a-rovin'? 
"A top challenge for the profession is re-defining the role of libraries and librarians in an environment in which Google, Amazon, Wikipedia and HathiTrust provide easier access and richer collections." - State of American Libraries Report, 2012
