I don’t recall who, a decade or so ago, first said that “in cyberspace, no one knows you’re a dog”; it’s as much true today that, in Second Life, no one knows that you’re anyone or anything other than your constructed persona.
At the time of writing (24 September 2007) there is both good news and bad with respect to diversity issues in Second Life. The good news is that you can be who or what you want to be, either because–like Ward Cunningham–you can leave your real-world [t.b.c.]
Equality
Equality and Diversity Toolkits from the Institute of Digital Learning, Newport, University of Wales
» http://equal.newport.ac.uk/SeriousGames_Eng.html
» http://www.mcvuk.com/press-releases/32903/ Newports-University-Sharing-Real-Research-in-Virtual-Worlds
» http://www.idl-equinex.newport.ac.uk/second_life_news.html
Disability
Text-to-speech for the visually impaired.

Further references
Bert De Coutere, ‘Second Life and education: what can we do?’, Learning2.0 : Journey to about2findout.com, 4th April 2007.
Alan Levine, ‘Role Play Activity… Next Stop, SLollywood?’, NMC Campus Observer, 18th July 2007