A long, long, time ago, in a country far, far, away, I played a game (or was a member of the community, if you will) called LambdaMOO. LambdaMOO was a blend of techno-utopian escapism, procrastination and hacker wizardry. Building on role-playing traditions, you connected to a text-only virtual world where none of the constraints of your mundane life applied.
Fifteen years later and a new wave of commercial virtual worlds sweeping the Internet in the form of Second life and it's ilk. Unlike traditional "games" these virtual worlds are not competitions, man-vs-monster or puzzle solving centred, they're community centred.
Second life is currently struggling with security issues, but there are much bigger potentially issues lying just under the surface. LambdaMOO lost much of it's appeal for many participants after the incident documented in Julian Dibbell's aptly titled "A Rape in Cyberspace," which evaporated the techno-utopian dreams and left the community traumatised. I certainly hope that Second life has a plan in place to deal with such situations.