This is amazing news. I was concerned that we would lose the ability to move easily between Windows/ OS X / Linux on the web. Now at least we have an open source framework, that gives us hope for the future.
To get an idea of what all this cool technology is, watch this video. Ely Greenfield from adobe draws an amazing diagram of the technologies involved, and shows which parts have been open sourced.
BTW, Robert has two videos here about the open source news here.
Here are some more interviews of related Adobe technologies.
PS. I guess this post of mine just proves how irrelevant Robert is! :)
Thanks to the slashdot thread, I found this site that lists some other open source flash related projects.