Accessibility / Section 508 with AJAX/Atlas

When people talk about Accessibility, I think of Section 508 and allowing blind/disabled people to use an application.  I put this small test of Atlas together for a blind friend of mine to test.  It is at http://216.187.235.116/atlassection508test/.  It seems that the applications runs find and he is able to see/hear the content using JAWS (www.freedomscientific.com).  So, the question is, what's the cause of the accessibility discussion with Atlas?  What are the issues?  I hear discussion but not statement of the issues.  Any information that you can provide would be appreciated.

Wally