We are trying to get as many Adobe developers who would like Acoustic Echo Cancellation (AEC) included in Flash to ask for it (or for Adobe to give us access to the RAW data from the microphone from which we can create our own AEC).
The more people who signup the more chance we have of Adobe including this in a new version of Flash 10 or through a plugin.
If you are experiencing Echo in AS and you would like your users to experience clear echo-free speech please come and join these threads:
Please regsiter, and then you can Vote, Watch and Comment from the left hand navigation bar.
Since it's been nearly six months since this topic was opened and the issue hasn't been properly addressed, I think a kick of this topic is in place. If you have problems with the lack of (proper) Acoustic Echo Cancellation (AEC) then please join the request in the above mentioned URL's.