FAS (The Federation of American Scientists) has a Virtual Worlds Almanac wiki for people to use. Teachers and students can to here to find information about many virtual worlds.
"We hope this will make it easier for the community to collaborate and to keep abreast of innovations and new product offerings," said FAS President Henry Kelly in a press release. "FAS is interested in the potential virtual worlds offer for education and learning."
I would be interested in hearing from teachers who are using virtual worlds, such as Second Life, in their teaching contacting me.