Even in domains other than language learning, the value of communicating is important. For instance, in mathematics learning being able to verbally explain results and problem solving steps is increasingly emphasized. Competencybased learning as, among others, put forward by Niss [27] regards communication of results as similar important as formal proving skills.
On the other hand, having the learners engaged in an unrestricted community can be distracting. During our microblogging usage, learners suddenly started to post German and Japanese messages, which in itself is no bad thing but distracted from the goal of practicing English. Additionally, unmoderated contributions can be problematic if offending content is posted. However most Web 2.0 services have builtin quality control mechanisms.