This is new – Kitely virtual worlds.
Some colleagues are suggesting that it is a good option for including virtual worlds in education
I have some reservations about the Facebook linkage – I think Facebook has way too much information about their users and I would be very hesitant to “require” kids to have Facebook accounts. I actively discourage my students from using Facebook for anything but convenient “public” communication.
There are charges but these seem modest.
Other than that, Kitely sounds like fun. There are many good folks contributing to the OpenSim platform, so this may be the next big thing.