Direct from Adobe: "Our current schedule for releasing the final version of Flash Player 9 for Linux is early 2007. Many readers have understandably requested a beta version before that time."
Yes, we do plan to release a beta version in advance of the final version. However, it will be a beta in the classical software engineering sense-- i.e., a version that we believe to be largely bug-free and submitted to the users in the hopes that the last of the bugs will be found and reported.
Why are we stubbornly refusing to release, say, an alpha version now? Primarily because there are known bugs in the Linux Flash Player, and because we know what the bugs are, and we are on track to fix these known bugs. If we were to release an alpha now, we would likely be inundated with reports about bugs we already know about. We think that processing such redundant reports would not necessarily be the most industrious use of our time.
So, the beta will come. Watch this space. http://blogs.adobe.com/penguin.swf/