I must confess I'm getting a little tired of the way people seem to be tying up their sense of self with either Flash or 'no-Flash'. For me, as a web developer and graphic designer, the biggest benefit of the Web Effects stack (I use that term deliberately because most of the capabilities come from parts of the rendering stack that are not HTML 5) is that there is a single rendering system to think about.
Consider that for a second. Instead of having to realise a design using CSS applied to a DOM, and then realise it again in Flash, I can use one suite of technologies all the way down. This allows me to do progressive enhancement. This allows me to apply my understanding of the box model to everything (reducing risks of impedance mismatches). This allows me to mix, for example, MathML with SVG with CSS level 3 modules with Javascript with HTML 5. In fact, something I am working on now does mix all those technologies together. The system has fewer 'boilerplate' conversions between its components, reducing the complexity for debugging. Surely that is a technological advantage those of us who claim to be designers or developers should rejoice in?
I am sure there are things that Flash can do that the Web Effects stack will never be able to do. That is fine, but I believe we should be working towards an 80/80 rule; use Flash if nothing else will do, but for the 80% of features that are used by designers 80% of the time, let us go for something simpler to understand, simpler to debug and simpler to maintain.
On another, but related, note very few people here seem to understand how the W3C process works - HTML 5 does not need to be 'ratified' (I guess what is meant here is 'become a Recommendation') before it is implemented; in fact, quite the opposite. Part of the criteria for progression of a specification to even Proposed Recommendation is that there exist a number of interoperable implementations of the majority of the specification. W3C specifications both drive and are driven by the implementor and user communities. Many of the technologies in these demos are not part of HTML 5 anyway (but rather part of CSS) and are following their own track. Thankfully, if you're following best practices then you do not need to adopt an all-or-nothing approach, and can provide an enhanced experience for your users capable of seeing it without degrading the experience of those who cannot.