I have never have I seen so much hysteria as that which surrounds the subject of Flash and it's support for Accessibility. This week I received an email recommending that we drop our use of Adobe Flash/AIR (we use it in our gadgets). (It was not a customer). The basis of the recommendation came from the results of a survey that can be found here. The survey itself is very good - but is not controlled (i.e. 1000 users were asked about their experiences).
My response to the team was quite simple: Accessibility is not a feature of the tooling - it's what you have to, as a responsible developer (and by that I mean anyone involved in the production of software) consider when designing, writing, testing your application. If you don't design the UI to cater for the needs of different individuals - then there is nothing that Flex/AIR/ADF/JSF/AJAX can do to improve that. Likewise, it is not the function of one department to add Accessibility to your product either.
Andrew Kirkpatrick of Adobe has posted a brilliant write up on the use of Flash and Accessibility. I recommend that you read it, especially when the next person starts pressing the alarm bells over the use of Flash.
Andrew's blog can be found here: WebAIM Screen Reader Survey: A closer looks at Flash and PDF results