I'll be the first to admit that I don't really get Second Life. I have tried the free component of it a year ago and it didn't really grab me as I have enough trouble trying to keep my first life in order and I quickly discovered that Second Life is not a Video Game as such although I can see the escapism, experimentation and adventure it offers users much like a traditional video game.
However Brett Bixler and a large number of other Educators have invested a gret deal of time and effort into exploring the educational potential of Second Life as an educational tool. I have seen a colleague have some success using Second Life to help her students learn Indonesian. She set up a school server that replicated some Indonesian Cities and let them use the environment to communicate in the native tongue and the kids loved it.
Brett has written a great paper on the potential of Second Life as an Educational Tool and explores the pro's and cons it offers. It is very thorough and non-biased and could assist others experimenting in this field.
I would love to hear from others who have experimented with Second Life and hear their successes or failures.