This paper reports on a research project investigating the deployment of two different wikis in two Masters of IT subjects. As well, two different learning task designs were used (weekly whole class extension question tasks versus semester long group projects) providing further basis for comparison and contrast within the project. Data collection mechanisms included a 22 item student survey, interviews with academics and observations on student contributions to the wikis. Key results regarding students' patterns of behaviour, the impact of learning task design upon contributions, the effect of training, and the quality of the wiki applications themselves are discussed. Based on these results, a set of 12 principles for implementing wiki based learning tasks are recommended.