A poster/pdf from K.Mancuso and J.Cole introducing guidelines for accessibility in virtual worlds is online here…http://www.gimpgirl.com/ – it was presented at the 2009 IEEE Accessign the Future Conference (Boston) – more information about the conference is here http://ewh.ieee.org/conf/accessingthefuture/

See also this long post at http://blogs.educationau.edu.au/kjohnson/2009/10/12/accessiblity-for-the-differently-abled-in-virtual-environments/ 

Also  – see the bibliography on the ‘constructing disability in online worlds’ paper at this blog, for more references and resources on this topic.