the thing is
There isn't really a version number for HTML, not in any meaningful sense. What there is, is browser support for a variety of features, depending on the browser. As a developer, you can only use elements which are well supported by the majority of browsers - you can't just say "let's use html5 or html4 or xhtml or whatever", you make decisions based on what (rough) percentage of users will or won't be able to use your site. You don't say "we'll use HTML5 for this", you say "we'll use <canvas> because it's an intranet site and we know that company runs the latest version of Chrome on it's desktops" or "we'll need to use Flash for this because we can't rely on enough users for the client to be happy having support for the <video> tag"
Hixie is right on dropping the version number. It's meaningless and always has been for the whole 15 years I've been making websites for a living.
The silly logo and so on is just pointless noise from Marketing hats who want to brand everything so they can talk about it and pretend to be techies. Thanks to this kind of nonsense, there will be studios all over the world where clients are demanding "the site must be html5" because they've heard of it and feel clever when they use acronyms and numbers, then the sound of facepalming devs will echo shortly after. Dropping any sort of version number will help this problem.