We survey here the state-of-the-art in open courseware initiatives worldwide. First, the MIT OpenCourseWare project is overviewed, as it has been the real starting point of the OCW movement. Usually, open courseware refers to a free and open digital publication of high quality university level educational materials that are organized as courses, and include course planning materials, evaluation tools, and thematic content, under a Creative Commons license. OCW is free and open, accessible to anyone, anywhere, and anytime via the Internet. The OCW initiative started in 2002, and it has been followed by many more programs that offer open access to courseware: Carnegie Mellon Open Learning Initiative, Harvard Medical School's MyCourses, Webcast.Berkeley, Rice University's Connexions, OpenCourseWare Consortium, Open Education Resources Commons, and The Saylor Foundation's Free Education Initiative, along with other major open courseware projects worldwide. The prospects for futur development of open courseware are taken into consideration, while its potential to provide for both social construction of knowledge and for development of open educational models, and therefore for E-Learning 2.0 and Web 2.0 is emphasized.