Adobe has done good work to help automatically determine accessibility information and expose it to assistive technologies. Unfortunately, because the feature is not turned on by default many sites that would benefit are left completely inaccessible.
I have been watching this Flex accessibility issue
for quite some time now. Today I received a notification that the item has been "deferred" which means for the time being Adobe Flex will continue being inaccessible by default. I don't know any other technology that has made this choice.
For those of you reading that want to know how to turn accessibility on see ...