Goold, A., Coldwell, J., and Annemieke, C. (2010). An examination of the role of the e-tutor. Australasian Journal of Educational Technology, 26(5), 704-716 (full-text).
Work on the e-tutor's role seems to have been silent over the last few years, so Goold et al's article is timely and will hopefully lead to further studies. The article focuses particularly on the online tutor's role where asynchronous discussion is required; it would be interesting to see work relating to the breadth of online tutoring roles as well.
Of particular note is the use of team-teaching, which doubtless made it possible to deal with 70+ students per module!