Library 2.0 has been a phenomenon that has been under discussion for almost four years. Perheps oddly, perhaps illustratively enough there has been many attempts to present definitions of the term. Most of the definitions so far have been, however, individuals' personal views of that what the 2.0 of library is all about. An article weitten by me together with my colleagues describing a definition based on empirical study of library and information professionals has been published in the Journal of Documentation (Vol 65, Number 4, pp. 668-681).