At the end of 2007, I was researching functional test tools (preferably open source) for testing Flash or Flex applications.
As I was familiar and very satisfied with Selenium for testing Web Applications I decided to put some effort on trying to use Selenium for driving my Web Flex Application functional tests.
With some work (in fact not too much work—kudos to Selenium) I had a working solution and was successfully using Selenium to test a deployed Web application with a Flash component (SWF).
As a result of this effort, Flash-Selenium has been created and open sourced.
http://code.google.com/p/flash-selenium/
Also a recent article on adobe.com describes Flash-Selenium usage in more details:
http://www.adobe.com/devnet/flash/articles/flash_selenium.html