The many-to-many social communication activity on the popular technology-news website Slashdot has been studied. We have concentrated on the dynamics of message production without considering semantic relations and have found regular temporal patterns in the reaction time of the community to a news-post as well as in single user behavior. The statistics of these activities follow log-normal distributions. Daily and weekly oscillatory cycles, which cause slight variations of this simple behavior, are identified. The findings are remarkable since the distribution of the number of comments per users, which is also analyzed, indicates a great amount of heterogeneity in the community. The reader may find surprising that only two parameters, those of the log-normal law, allow a detailed description, or even prediction, of social many-to-many information exchange in this kind of popular public spaces. KEYWORDS Social interaction, information diffusion, log-normal activity, heavy tails, Sl...