TELearn 2009 has successfully attracted over 91 submissions, from 4 continents, 11 countries. Half of the submissions came from the outside of Taiwan, which indicates TELearn has become a truly international event. This year, TELearn accept 18 full papers, the acceptance rate of full papers is less than 20%. From the 18 full papers, 5 best papers from Japan, Taiwan, USA, Finland and South Africa were included in this special issue to contribute the understanding of social computing in e-learning and raise potential questions which will require reflection.