Alan Miller and Ishbel Duncan are running a special session at CSEDU 2013 (in May in Aachen) on using Virtual Worlds for learning. Levels of learning, applicable learning theories, student interaction, avatar interaction, learning contexts and evaluation are all open for discussion.
The due date for papers is February 27 2013 and more information can be found on
http://www.csedu.org/SpecialSessions.aspx#VWIL