Hard to believe it's been two years since I posted! I expect to be writing more regularly moving forward. Not that the bar is very high at this point :)
Over the past few years I've helped write a few papers related to distributed virtual environments in various workshops. In case you're interested, here's pointers:
The Near-Term Feasibility of P2P MMOG's. There's been a lot of research on creating peer-to-peer distributed virtual environments, e.g. a P2P version of World of Warcraft. Using World of Warcraft traffic patterns and UK consumer broadband capabilities, this paper suggests that it's not possible to operate a pure P2P massively multiplayer game on today's internet.
Group Movement in World of Warcraft Battlegrounds and Avatar Movement in World of Warcraft Battlegrounds. These two papers examine movement of actual player avatars in World of Warcraft, specifically in battlegrounds. They suggest that previous models of avatar movement are inconsistent with observed behaviors. This is relevant for tasks such as workload evaluation and simulation of online games.