Ok, there has to be One Authority, I buy that. Joel implies that since we don't have that now we can never have one. Maybe I'm being an idealist in my own way, but why can't we have this super strict implementation? The w3c has some resources, right?
Can't the standards people pressure them to create this reference implementation? It doesn't have to be fast, or have any features or anything. It just needs a viewport, back button, a way to point it at an url and to be Official. (also, scriptability would be awesome). It wouldn't fix old web pages, but it could stop the spread of new problems.
Hmm. On second though, it's probably more likely that the w3c would give us all ponies...
How about this: nobody use html 5 until we've got our reference. Promise?