Last year, I participated in an EU-funded teacher training Project in Second Life called MUVEnation. One of the activities we did was to collect, test and describe educational tools in SL. These were compiled and reviewed and will soon (probably end of March) be published in a book as an Open Educational Resource under CC licence. There is more information on the project website.
Here is a list of all the dissemination activities of the MUVEnation project.