The idea of Library 2.0 originated from the concept of Web 2.0 social interactions within the Web. From this aspect, Library 2.0 is a library blended with Web 2.0. The most remarkable features of Library 2.0 are interactions and user involvement. Users' roles in new library environments are greater since they can contribute to establishing a library collection by annotating, blogging, reviewing, etc. While users’ roles become important, the responsibilities of the librarians increase due to the unfiltered information created by users. Librarians now should extend their roles as information creators, organizers, providers, managers, as well as moderators. In this paper, we reviewed the current literature on the new paradigm of digital libraries, Library 2.0, and the development of Library 2.0. In addition, we discuss the extended role of the Librarian 2.0 in Library 2.0.