I read earlier this year here that Adobe were going to release the specification of their proprietary protocol - RTMP.  I've incorporated flash into the development of mendmypc and although it's been a mixed experience, I have to say flash is the best when it comes to streaming audio and video and generally providing rich multimedia interfaces. 

I did experiment with the open source version of flash called Red5, however it's important to note that this development was done without the impending specifications.  The Red5 developers admit that there are things they don't know about RTMP and are essentially dependent on investigating the protocol to learn more. I am very hopeful that the release of these specifications will help the continued development of Red5. Flash will be much better for the innovation that open source will bring one case in point is the whole flash screen sharing/remote control fiasco.

My concern is that these specifications are still not forthcoming, is Adobe getting cold feet? They should not worry I'm sure they will still make loads of money from their corporate customers.