Yes, Ross I'm a Flash developer.

My information comes from Colin Moock (Flash Guru). He has just published
a book called "Action Script for Flash MX" with O'Rielly, 2003.

Here is what he says:
"The Accessibility object manages communication between the Flash Player
and screen readers or accessibility aids such as G W Micro's Window-Eyes.
The isActive() method checks whether an accessibility aid is communicating
with the Flash Player. It is useful when dynamically generating content in
a movie based upon the presence of accessibilty support. The sendEvent()
method allows you to send information about user interface component
events to accessibility aids and is intended for developers of accessible
user interface components."

"At the time of this writing, the Macromedia ActionScript Component
Accessibilty (M A S C A) A P I works with Microsoft Active Accessibility
(M S S A) only; hence, only the Active X version of Flash Player 6
supports communication with an external accessibility application. In the
future, more versions of the Flash Player are likely to include support.
Use of the M A S C A A P I requires some knowledge of M S A A. To
determine whether the current Player has accessibilty support, use (the
ActionScript property) capabilites.hasAccessibility. ..."

"Many of the Accessibility implementation details have yet to be fully
exposed to the developer community. ... As third-party component
development proliferates, Macromedia plasnto publish accessibilty
specifications and tutorials. For more information on accessibilty in
Flash, see:
http://www.macromedia.com/macromedia/accessibility/features/flash/"

I hope this helps.