I've just finished reading Mikael Jakobsson's dissertation (Informatics, Umeå University, 2006) with the abovementioned title. It's an easy read, which gives a good survey of what it's like in online environments, with quite a few things I found really interesting. Micke has looked at three different online environments: the two-dimensional The Palace, and the three-dimensional Active Worlds and Everquest. Although his background is different from mine, we still seem to have had similar experiences in online worlds.
Although he was mainly in charge of the building and programming, he soon realised that the social implications of whatever he programmed were huge. He realised that the virtual/real dichotomy simply does not hold. Although the arena is a digital one, with everything built pixel by pixel, the interaction in a digital environment is nevertheless between two or more people — real flesh-and-blood people — and as such the interaction can never be "virtual" as in make-belief. There are indeed differences between how people interact in the digital and physical worlds, but there are also similarities, and I will try to incorporate his idea of levity (the "lightness" of the medium, the idea that actions inworld have no consequences) into my own discussion about why people don't seem to hesitate to openly perform controversial acts inside Second Life, acts they most likely would hesitate to carry out in their everyday, physical environment. I will also, together with Micke, argue that the appearance of levity sometimes is deceiving, however. Actions inworld do have consequences. My research shows that the apparent ease, with which it's possible to change identity inworld, is indeed counteracted by the online community's need for stable and reliable identities/group members. Someone with a new or unstable online identity is easily perceived as a threat to already established groups, and might, if he or she does not prove themselves worthy of trust, end up a loner.