From the abstract of an article "Learning together apart: Distance education in a virtual world" (citation) by myself and my colleague Kim Holmberg published in First Monday:
A course in information studies was partly held in the virtual world of Second Life. Second Life was used as a platform to deliver lectures and as a place for organizing group assignments and having discussions. Students’ opinions about Second Life were studied and compared to their opinions about more traditional methods in education. The results show a lower threshold for participation in lectures. According to the students, Second Life should not replace face–to–face education, but it could serve as an excellent addition to other more traditional methods and platforms used in education. The students also considered that lectures held in Second Life were much more “fun” than those using other methods. This particular aspect, and its effect on learning outcomes, requires further research. This research demonstrates that Second Life has potential as a learning environment in distance education.