Dean here... so, we (on the IE team) are reading the comments. First, thanks for the feedback. There's a lot of passion, especially about what video formats C9 videos are in, and how easy it is to get one format or another. There's some great conversation going on here (e.g. how many different engines there are, and the difference between everyone and 8% (http://channel9.msdn.com/posts/Charles/IE-9-Standards-and-Interoperability/?CommentID=507427).
Getting people to switch up from IE6 to IE8 (or even IE7) is something we all seem to agree about. There are a lot of good reasons: security, performance, as well as the benefits to developers. As excited as anyone who read Channel9 is to get the latest software on our own machines, remembering that not everyone is a developer is important too. There's another post here http://blogs.msdn.com/ie/archive/2009/08/10/engineering-pov.aspx about that topic.
Have folks looked over at the W3C CSS 2.1 working group and the discussions there about test suites and real-world usage patterns? I think there's some valuable material with respect to delivering on interoperable standards. What else is on C9ers' minds?