Rosenburg, A. (2010). Virtual World Research Ethics and the Private/Public Distinction. International Journal of Internet Research Ethics, 3(1). Retrieved from http://ijire.net/issue_3.1/3_rosenberg.pdf.
The paper discusses a study in Second Life on the boundary between public and private within Second Life. This is relevant to the ethics of research because if something is public it does not need to be treated with the same level of care when reporting (e.g. anonymising, obtaining consent etc) as private discourse. In fact, the two assumptions that the study is based on are listed as that researchers shouldn't do any harm to anyone, and that the public/private boundary is important to avoid doing harm.
The author outlines two simplified extremes of view: public is publicly accessible, or public is if perceived as public by the participants. The first argument makes all online interaction in MMOGs or virtual worlds public, as it could be accessed by anyone who wants to. However, the study shows that the people using the spaces had clear ideas of which parts of their environment and (interestingly) communication methods were more private than others.
The main thing I think I can take from this paper is that you need to know your environment before you can judge what would be considered 'crossing the line' with participants. There is still a struggle as well between being open with your participants that you are studying them, and missing parts of what they do because they modify their behaviour for the study.
Also the writer spent a year spending between 10 and 30 hours a week in Second Life. Where am I going to find that kind of time?!