Despite the fact that portability was perceived as one of the major benefits of podcasting as a teaching and learning tool, little evidence has been found of users taking advantage of this feature for academic use. This paper reports on a major study (1886 responses) of iTunes U users. The analysis compares the responses of those participants who use static devices to play the materials they download with those of users who utilise mobile devices. The results show that more users play iTunes U materials from mobile devices than static devices. Users share some similarities in their use of podcasts but some marked differences as well, in contrast with previous research. The author argues that different perceptions and practices are based on whether the users are formal or informal learners and discuss the implications for the use of podcasting as a mobile learning technology.