Hi Vincent,
This would be for us a real improvement since we had already hack
XWiki to have it more accessible than it was for a previous client,
and we will audit and improve that effort soon, when we will upgrade
that client to your latest release (or at least 1.9 depending on
timeframe).
The fields that we have worked on is improving navigation of a page
without style, ensuring as best as we could proper reading of the page
by readers for disabled peoples. Mostly, this had required a patch in
the way object fields are displayed, and many small adjustment in the
velocity templates (using a custom skin and some direct patch). Of
course, we have not produced a full XWiki compliant solution, but the
public part of our site is known to be accessible. You can see it
there:
http://elsaccessible.com