This is encouraging because it means that others are considering SL in the same way as us, but particularly interesting were the comments from one user who observed that blind people can't even create an account, let alone use the client!
Also Reported on this site is that Judy Brewer, Director of the Web Accessibility Initiative (WAI), World Wide Web Consortium (W3C), gave a presentation at a Second Life conference sponsored by the U.S. Department of State Bureau of International Information Programs (IIP) and the University of Southern California Annenberg School for Communication. She is reported as saying the following,
"If a person has a visual disability, they need an alternative to the visual environment on Second Life. Maybe a space could be magnified to make it easier to see. A speech reader could speak the text typed into the chat."
"There need to be easy and reliable ways to be able to add text descriptions to all content created in SL."
Additionally I read the BBC's article on the IBM's "Accessibility In Virtual Worlds" project by Extreme Blue and the Human Ability and Accessibility Centre, which uses Active Worlds rather than SL as it can be run within a web browser (although when I tried it simply launched an external browser).
"When the user comes into the world, the items are described as well as their positions," explained Colm O'Brien, one of the team of four researchers who worked on the project.
"There is also sound attached - for example, if there's a tree nearby you will hear a rustling of leaves," said Mr O'Brien.
The work also developed tools which uses text to speech software that reads out any chat from fellow avatars in the virtual world that appears in a text box.
Characters in the virtual world can have a "sonar" attached to them so that the user gets audible cues to alert them to when they are approaching, from which direction and how near they are.
The BBC provide an audio example of the interface, and there's a section on Radio 4's In Touch programme with interviews from interns Esmond Walsh and Antony Clinton, though unfortunately I can't source any more information about this fascinating sounding project.